diff --git a/app/main/validators.py b/app/main/validators.py
index 131c70a77..f9b2de0cc 100644
--- a/app/main/validators.py
+++ b/app/main/validators.py
@@ -61,7 +61,7 @@ class ValidEmail:
 
 
 class NoCommasInPlaceHolders:
-    def __init__(self, message="You cannot put commas between double brackets"):
+    def __init__(self, message="You cannot put commas between double parenthesis"):
         self.message = message
 
     def __call__(self, form, field):
diff --git a/app/templates/partials/templates/guidance-optional-content.html b/app/templates/partials/templates/guidance-optional-content.html
index d3bc0dba5..6b74effcb 100644
--- a/app/templates/partials/templates/guidance-optional-content.html
+++ b/app/templates/partials/templates/guidance-optional-content.html
@@ -7,7 +7,7 @@
 </h3>
 <div id="m-a2" class="usa-accordion__content usa-prose">
   <p class="usa-body">
-    Use double brackets and ‘??’ to define optional content.
+    Use double parenthesis and ‘??’ to define optional content.
   </p>
   <p class="bottom-gutter-1-3">
     For example if you only want to show something to people who are under
diff --git a/app/templates/partials/templates/guidance-personalization.html b/app/templates/partials/templates/guidance-personalization.html
index bc6a358a5..0c11906cd 100644
--- a/app/templates/partials/templates/guidance-personalization.html
+++ b/app/templates/partials/templates/guidance-personalization.html
@@ -7,11 +7,10 @@
 </h3>
 <div id="personalization" class="usa-accordion__content usa-prose">
   <p class="bottom-gutter-1-3">
-    Use double brackets to personalize your message:
+    Use double parenthesis to personalize your message:
   </p>
   {{ usaInsetText({
     "text": "Hello ((first name)), your reference is ((ref number))",
     "classes": ""})
   }}
 </div>
-
diff --git a/app/templates/partials/templates/guidance-send-a-document.html b/app/templates/partials/templates/guidance-send-a-document.html
index 3f839e378..d9841869a 100644
--- a/app/templates/partials/templates/guidance-send-a-document.html
+++ b/app/templates/partials/templates/guidance-send-a-document.html
@@ -4,7 +4,7 @@
   Send a document by email
 </h2>
 <p class="usa-body">
-  Use double brackets to add a placeholder field to your template. This will contain a secure link to download the document.
+  Use double parenthesis to add a placeholder field to your template. This will contain a secure link to download the document.
 </p>
 {{ usaInsetText({
   "text": "Download your document at: ((link_to_file))",
diff --git a/app/templates/views/check/column-errors.html b/app/templates/views/check/column-errors.html
index a24b5de3e..bcb518892 100644
--- a/app/templates/views/check/column-errors.html
+++ b/app/templates/views/check/column-errors.html
@@ -102,7 +102,7 @@ Error
   <div class="usa-alert usa-alert--error" role="alert">
     <div class="usa-alert__body">
       <h1 class="usa-alert__heading banner-title" data-module="track-error" data-error-type="Missing placeholder columns"
-        data-error-label="{{ upload_id }}">Your column names need to match the double brackets in your template</h1>
+        data-error-label="{{ upload_id }}">Your column names need to match the double parenthesis in your template</h1>
       <p class="usa-alert__text">
         Your file is missing {{ recipients.missing_column_headers | formatted_list(
         conjunction='and',
diff --git a/app/templates/views/how-to/edit-and-format-messages.html b/app/templates/views/how-to/edit-and-format-messages.html
index 7b1cab01c..d018aaa1c 100644
--- a/app/templates/views/how-to/edit-and-format-messages.html
+++ b/app/templates/views/how-to/edit-and-format-messages.html
@@ -61,7 +61,7 @@
   <ol class="list list-number">
     <li>Go to the {{ service_link(current_service, 'main.choose_template', 'templates') }} page.</li>
     <li>Add a new template or choose an existing template and select <b class="bold">Edit</b>.</li>
-    <li>Add a placeholder using double brackets. For example: Hello ((first&nbsp;name)), your reference is ((ref&nbsp;number)).</li>
+    <li>Add a placeholder using double parenthesis. For example: Hello ((first&nbsp;name)), your reference is ((ref&nbsp;number)).</li>
     <li>Select <b class="bold">Save</b>.</li>
   </ol>
 
@@ -81,7 +81,7 @@
   <ol class="list list-number">
     <li>Go to the {{ service_link(current_service, 'main.choose_template', 'templates') }} page.</li>
     <li>Add a new template or choose an existing template and select <b class="bold">Edit</b>.</li>
-    <li>Use double brackets and ?? to define optional content. For example, if you only want to show something to people who are under 18: ((under18??Please get your application signed by a parent or guardian.))</li>
+    <li>Use double parenthesis and ?? to define optional content. For example, if you only want to show something to people who are under 18: ((under18??Please get your application signed by a parent or guardian.))</li>
     <li>Select <b class="bold">Save</b>.</li>
   </ol>
 
diff --git a/app/templates/views/how-to/index.html b/app/templates/views/how-to/index.html
index aa2361cb6..847dc03ce 100644
--- a/app/templates/views/how-to/index.html
+++ b/app/templates/views/how-to/index.html
@@ -59,7 +59,7 @@ your recipient to manage their benefits and increase follow-through.</p>
 
 <h3>To personalize your content</h3>
 <ol class="list">
-  <li>Add a placeholder to your content by placing two brackets around the personalized elements.</li>
+  <li>Add a placeholder to your content by placing two parenthesis around the personalized elements.</li>
   <li>You can manually enter the personalized content or you can upload a spreadsheet with the details and let Notify do the
   work for you.</li>
 </ol>
@@ -78,7 +78,7 @@ all or part of the message contingent upon specific criteria associated with the
 
 <h3>To add conditional content</h3>
 <ol class="list">
-  <li>Use two brackets and ?? to define the conditional content.</li>
+  <li>Use two parenthesis and ?? to define the conditional content.</li>
   <li>You can manually enter the conditional content or you can upload a spreadsheet with the personal details and let Notify
   do the work for you.</li>
 </ol>
diff --git a/notifications_utils/field.py b/notifications_utils/field.py
index c0ea50216..ff7f95f57 100644
--- a/notifications_utils/field.py
+++ b/notifications_utils/field.py
@@ -14,7 +14,7 @@ from notifications_utils.insensitive_dict import InsensitiveDict
 
 class Placeholder:
     def __init__(self, body):
-        # body shouldn’t include leading/trailing brackets, like (( and ))
+        # body shouldn’t include leading/trailing parenthesis, like (( and ))
         self.body = body.lstrip("(").rstrip(")")
 
     @classmethod
@@ -70,14 +70,16 @@ class Field:
     conditional_placeholder_tag = (
         "<span class='placeholder-conditional'>(({}??</span>{}))"
     )
-    placeholder_tag_no_brackets = "<span class='placeholder-no-brackets'>{}</span>"
+    placeholder_tag_no_parenthesis = (
+        "<span class='placeholder-no-parenthesis'>{}</span>"
+    )
     placeholder_tag_redacted = "<span class='placeholder-redacted'>hidden</span>"
 
     def __init__(
         self,
         content,
         values=None,
-        with_brackets=True,
+        with_parenthesis=True,
         html="strip",
         markdown_lists=False,
         redact_missing_personalisation=False,
@@ -85,8 +87,8 @@ class Field:
         self.content = content
         self.values = values
         self.markdown_lists = markdown_lists
-        if not with_brackets:
-            self.placeholder_tag = self.placeholder_tag_no_brackets
+        if not with_parenthesis:
+            self.placeholder_tag = self.placeholder_tag_no_parenthesis
         self.sanitizer = {
             "strip": strip_html,
             "escape": escape_html,
@@ -198,7 +200,7 @@ class PlainTextField(Field):
 
     placeholder_tag = "(({}))"
     conditional_placeholder_tag = "(({}??{}))"
-    placeholder_tag_no_brackets = "{}"
+    placeholder_tag_no_parenthesis = "{}"
     placeholder_tag_redacted = "[hidden]"
 
 
diff --git a/notifications_utils/jinja_templates/letter_pdf/_main_css.jinja2 b/notifications_utils/jinja_templates/letter_pdf/_main_css.jinja2
index c73684d32..f8dc57643 100644
--- a/notifications_utils/jinja_templates/letter_pdf/_main_css.jinja2
+++ b/notifications_utils/jinja_templates/letter_pdf/_main_css.jinja2
@@ -169,7 +169,7 @@
     border-radius: 1.05em;
   }
 
-  .placeholder-no-brackets {
+  .placeholder-no-parenthesis {
     display: inline;
     background: #FD0;
     color: #000;
diff --git a/notifications_utils/sanitise_text.py b/notifications_utils/sanitise_text.py
index 3e9da0764..8c1d1af36 100644
--- a/notifications_utils/sanitise_text.py
+++ b/notifications_utils/sanitise_text.py
@@ -68,7 +68,7 @@ class SanitiseText:
         if decomposed != "" and "<" not in decomposed:
             # decomposition lists the unicode code points a character is made up of, if it's made up of multiple
             # points. For example the á character returns '0061 0301', as in, the character a, followed by a combining
-            # acute accent. The decomposition might, however, also contain a decomposition mapping in angle brackets.
+            # acute accent. The decomposition might, however, also contain a decomposition mapping in angle parenthesis.
             # For a full list of the types, see here: https://www.compart.com/en/unicode/decomposition.
             # If it's got a mapping, we're not sure how best to downgrade it, so just see if it's in the
             # REPLACEMENT_CHARACTERS map. If not, then it's probably a letter with a modifier, eg á
diff --git a/notifications_utils/template.py b/notifications_utils/template.py
index ec112173f..186733797 100644
--- a/notifications_utils/template.py
+++ b/notifications_utils/template.py
@@ -376,7 +376,7 @@ class SMSPreviewTemplate(BaseSMSTemplate):
                     "recipient": Field(
                         "((phone number))",
                         self.values,
-                        with_brackets=False,
+                        with_parenthesis=False,
                         html="escape",
                     ),
                     "show_recipient": self.show_recipient,
@@ -691,7 +691,7 @@ class EmailPreviewTemplate(BaseEmailTemplate):
                     "from_address": self.from_address,
                     "reply_to": self.reply_to,
                     "recipient": Field(
-                        "((email address))", self.values, with_brackets=False
+                        "((email address))", self.values, with_parenthesis=False
                     ),
                     "show_recipient": self.show_recipient,
                 }
@@ -779,7 +779,7 @@ class BaseLetterTemplate(SubjectMixin, Template):
             self.address_block,
             self.values,
             html="escape",
-            with_brackets=False,
+            with_parenthesis=False,
         ).splitlines()
 
     @property
diff --git a/tests/app/main/test_validators.py b/tests/app/main/test_validators.py
index aaa79ad40..83f040fa5 100644
--- a/tests/app/main/test_validators.py
+++ b/tests/app/main/test_validators.py
@@ -56,7 +56,7 @@ def test_for_commas_in_placeholders(
 ):
     with pytest.raises(ValidationError) as error:
         NoCommasInPlaceHolders()(None, _gen_mock_field("Hello ((name,date))"))
-    assert str(error.value) == "You cannot put commas between double brackets"
+    assert str(error.value) == "You cannot put commas between double parenthesis"
     NoCommasInPlaceHolders()(None, _gen_mock_field("Hello ((name))"))
 
 
diff --git a/tests/app/main/views/test_send.py b/tests/app/main/views/test_send.py
index d957fa393..ac81050ad 100644
--- a/tests/app/main/views/test_send.py
+++ b/tests/app/main/views/test_send.py
@@ -775,7 +775,7 @@ def test_upload_csv_file_with_very_long_placeholder_shows_check_page_with_errors
             +12028675109
         """,
             (
-                "Your column names need to match the double brackets in your template "
+                "Your column names need to match the double parenthesis in your template "
                 "Your file is missing a column called ‘name’."
             ),
         ),
diff --git a/tests/notifications_utils/test_formatters.py b/tests/notifications_utils/test_formatters.py
index 61185d974..4a4119fa2 100644
--- a/tests/notifications_utils/test_formatters.py
+++ b/tests/notifications_utils/test_formatters.py
@@ -232,8 +232,8 @@ def test_bleach_doesnt_try_to_make_valid_html_before_cleaning():
         # We let users use &amp; because it’s often pasted in URLs
         ("?a=1&amp;b=2", "?a=1&amp;b=2"),
         # We let users use &lpar; and &rpar; because otherwise it’s
-        # impossible to put brackets in the body of conditional placeholders
-        ("((var??&lpar;in brackets&rpar;))", "((var??&lpar;in brackets&rpar;))"),
+        # impossible to put parenthesis in the body of conditional placeholders
+        ("((var??&lpar;in parenthesis&rpar;))", "((var??&lpar;in parenthesis&rpar;))"),
     ],
 )
 def test_escaping_html_entities(
diff --git a/tests/notifications_utils/test_markdown.py b/tests/notifications_utils/test_markdown.py
index be1053725..6363253df 100644
--- a/tests/notifications_utils/test_markdown.py
+++ b/tests/notifications_utils/test_markdown.py
@@ -44,9 +44,9 @@ def test_makes_links_out_of_URLs(url):
             ),
         ),
         (
-            ("this link is in brackets (http://example.com)"),
+            ("this link is in parenthesis (http://example.com)"),
             (
-                "this link is in brackets "
+                "this link is in parenthesis "
                 '(<a style="word-wrap: break-word; color: #1D70B8;" href="http://example.com">http://example.com</a>)'
             ),
         ),
diff --git a/tests/notifications_utils/test_placeholders.py b/tests/notifications_utils/test_placeholders.py
index 348d2159a..f155bd5e5 100644
--- a/tests/notifications_utils/test_placeholders.py
+++ b/tests/notifications_utils/test_placeholders.py
@@ -8,8 +8,8 @@ from notifications_utils.field import Placeholder
 @pytest.mark.parametrize(
     ("body", "expected"),
     [
-        ("((with-brackets))", "with-brackets"),
-        ("without-brackets", "without-brackets"),
+        ("((with-parenthesis))", "with-parenthesis"),
+        ("without-parenthesis", "without-parenthesis"),
     ],
 )
 def test_placeholder_returns_name(body, expected):
diff --git a/tests/notifications_utils/test_recipient_validation.py b/tests/notifications_utils/test_recipient_validation.py
index ff48df775..f6747256e 100644
--- a/tests/notifications_utils/test_recipient_validation.py
+++ b/tests/notifications_utils/test_recipient_validation.py
@@ -136,7 +136,7 @@ invalid_email_addresses = (
     "local-with-’-apostrophe@domain.com",
     "local-with-”-quotes@domain.com",
     "domain-starts-with-a-dot@.domain.com",
-    "brackets(in)local@domain.com",
+    "parenthesis(in)local@domain.com",
     "email-too-long-{}@example.com".format("a" * 320),
     "incorrect-punycode@xn---something.com",
 )
diff --git a/tests/notifications_utils/test_template_types.py b/tests/notifications_utils/test_template_types.py
index 1b119f216..8942a619d 100644
--- a/tests/notifications_utils/test_template_types.py
+++ b/tests/notifications_utils/test_template_types.py
@@ -894,13 +894,13 @@ def test_phone_templates_normalise_whitespace(template_class):
         (
             {},
             [
-                "<span class='placeholder-no-brackets'>address line 1</span>",
-                "<span class='placeholder-no-brackets'>address line 2</span>",
-                "<span class='placeholder-no-brackets'>address line 3</span>",
-                "<span class='placeholder-no-brackets'>address line 4</span>",
-                "<span class='placeholder-no-brackets'>address line 5</span>",
-                "<span class='placeholder-no-brackets'>address line 6</span>",
-                "<span class='placeholder-no-brackets'>address line 7</span>",
+                "<span class='placeholder-no-parenthesis'>address line 1</span>",
+                "<span class='placeholder-no-parenthesis'>address line 2</span>",
+                "<span class='placeholder-no-parenthesis'>address line 3</span>",
+                "<span class='placeholder-no-parenthesis'>address line 4</span>",
+                "<span class='placeholder-no-parenthesis'>address line 5</span>",
+                "<span class='placeholder-no-parenthesis'>address line 6</span>",
+                "<span class='placeholder-no-parenthesis'>address line 7</span>",
             ],
         ),
         (
@@ -910,12 +910,12 @@ def test_phone_templates_normalise_whitespace(template_class):
             },
             [
                 "123 Fake Street",
-                "<span class='placeholder-no-brackets'>address line 2</span>",
-                "<span class='placeholder-no-brackets'>address line 3</span>",
-                "<span class='placeholder-no-brackets'>address line 4</span>",
-                "<span class='placeholder-no-brackets'>address line 5</span>",
+                "<span class='placeholder-no-parenthesis'>address line 2</span>",
+                "<span class='placeholder-no-parenthesis'>address line 3</span>",
+                "<span class='placeholder-no-parenthesis'>address line 4</span>",
+                "<span class='placeholder-no-parenthesis'>address line 5</span>",
                 "United Kingdom",
-                "<span class='placeholder-no-brackets'>address line 7</span>",
+                "<span class='placeholder-no-parenthesis'>address line 7</span>",
             ],
         ),
         (
@@ -1129,13 +1129,13 @@ def test_letter_image_renderer(
             "image_url": "http://example.com/endpoint.png",
             "page_numbers": expected_page_numbers,
             "address": [
-                "<span class='placeholder-no-brackets'>address line 1</span>",
-                "<span class='placeholder-no-brackets'>address line 2</span>",
-                "<span class='placeholder-no-brackets'>address line 3</span>",
-                "<span class='placeholder-no-brackets'>address line 4</span>",
-                "<span class='placeholder-no-brackets'>address line 5</span>",
-                "<span class='placeholder-no-brackets'>address line 6</span>",
-                "<span class='placeholder-no-brackets'>address line 7</span>",
+                "<span class='placeholder-no-parenthesis'>address line 1</span>",
+                "<span class='placeholder-no-parenthesis'>address line 2</span>",
+                "<span class='placeholder-no-parenthesis'>address line 3</span>",
+                "<span class='placeholder-no-parenthesis'>address line 4</span>",
+                "<span class='placeholder-no-parenthesis'>address line 5</span>",
+                "<span class='placeholder-no-parenthesis'>address line 6</span>",
+                "<span class='placeholder-no-parenthesis'>address line 7</span>",
             ],
             "contact_block": "10 Downing Street",
             "date": "12 December 2012",
@@ -1838,7 +1838,7 @@ def test_is_message_empty_email_and_letter_templates_tries_not_to_count_chars(
                 mock.call(
                     "subject", {}, html="escape", redact_missing_personalisation=False
                 ),
-                mock.call("((email address))", {}, with_brackets=False),
+                mock.call("((email address))", {}, with_parenthesis=False),
             ],
         ),
         (
@@ -1855,7 +1855,9 @@ def test_is_message_empty_email_and_letter_templates_tries_not_to_count_chars(
             "sms",
             {},
             [
-                mock.call("((phone number))", {}, with_brackets=False, html="escape"),
+                mock.call(
+                    "((phone number))", {}, with_parenthesis=False, html="escape"
+                ),
                 mock.call(
                     "content", {}, html="escape", redact_missing_personalisation=False
                 ),
@@ -1874,7 +1876,9 @@ def test_is_message_empty_email_and_letter_templates_tries_not_to_count_chars(
             "broadcast",
             {},
             [
-                mock.call("((phone number))", {}, with_brackets=False, html="escape"),
+                mock.call(
+                    "((phone number))", {}, with_parenthesis=False, html="escape"
+                ),
                 mock.call(
                     "content", {}, html="escape", redact_missing_personalisation=False
                 ),
@@ -1906,7 +1910,7 @@ def test_is_message_empty_email_and_letter_templates_tries_not_to_count_chars(
                         "((address line 7))"
                     ),
                     {},
-                    with_brackets=False,
+                    with_parenthesis=False,
                     html="escape",
                 ),
                 mock.call(
@@ -1937,7 +1941,7 @@ def test_is_message_empty_email_and_letter_templates_tries_not_to_count_chars(
                         "((address line 7))"
                     ),
                     {},
-                    with_brackets=False,
+                    with_parenthesis=False,
                     html="escape",
                 ),
                 mock.call(
@@ -1973,7 +1977,7 @@ def test_is_message_empty_email_and_letter_templates_tries_not_to_count_chars(
                 mock.call(
                     "subject", {}, html="escape", redact_missing_personalisation=True
                 ),
-                mock.call("((email address))", {}, with_brackets=False),
+                mock.call("((email address))", {}, with_parenthesis=False),
             ],
         ),
         (
@@ -1981,7 +1985,9 @@ def test_is_message_empty_email_and_letter_templates_tries_not_to_count_chars(
             "sms",
             {"redact_missing_personalisation": True},
             [
-                mock.call("((phone number))", {}, with_brackets=False, html="escape"),
+                mock.call(
+                    "((phone number))", {}, with_parenthesis=False, html="escape"
+                ),
                 mock.call(
                     "content", {}, html="escape", redact_missing_personalisation=True
                 ),
@@ -1992,7 +1998,9 @@ def test_is_message_empty_email_and_letter_templates_tries_not_to_count_chars(
             "broadcast",
             {"redact_missing_personalisation": True},
             [
-                mock.call("((phone number))", {}, with_brackets=False, html="escape"),
+                mock.call(
+                    "((phone number))", {}, with_parenthesis=False, html="escape"
+                ),
                 mock.call(
                     "content", {}, html="escape", redact_missing_personalisation=True
                 ),
@@ -2034,7 +2042,7 @@ def test_is_message_empty_email_and_letter_templates_tries_not_to_count_chars(
                         "((address line 7))"
                     ),
                     {},
-                    with_brackets=False,
+                    with_parenthesis=False,
                     html="escape",
                 ),
                 mock.call(
@@ -2488,7 +2496,7 @@ def test_email_preview_shows_reply_to_address(extra_args):
 @pytest.mark.parametrize(
     ("template_values", "expected_content"),
     [
-        ({}, "<span class='placeholder-no-brackets'>email address</span>"),
+        ({}, "<span class='placeholder-no-parenthesis'>email address</span>"),
         ({"email address": "test@example.com"}, "test@example.com"),
     ],
 )
@@ -2558,11 +2566,11 @@ def test_email_preview_shows_recipient_address(
             (
                 "<ul>"
                 "<li>line 1</li>"
-                '<li><span class="placeholder-no-brackets">address line 2</span></li>'
-                '<li><span class="placeholder-no-brackets">address line 3</span></li>'
-                '<li><span class="placeholder-no-brackets">address line 4</span></li>'
-                '<li><span class="placeholder-no-brackets">address line 5</span></li>'
-                '<li><span class="placeholder-no-brackets">address line 6</span></li>'
+                '<li><span class="placeholder-no-parenthesis">address line 2</span></li>'
+                '<li><span class="placeholder-no-parenthesis">address line 3</span></li>'
+                '<li><span class="placeholder-no-parenthesis">address line 4</span></li>'
+                '<li><span class="placeholder-no-parenthesis">address line 5</span></li>'
+                '<li><span class="placeholder-no-parenthesis">address line 6</span></li>'
                 # Postcode is not normalised until the address is complete
                 "<li>n1 4wq</li>"
                 "</ul>"