diff --git a/README.md b/README.md
index c317ada..9d24038 100644
--- a/README.md
+++ b/README.md
@@ -36,6 +36,7 @@ A selection of quality-of-life tools for use with [pre-commit](https://github.co
       - [2.6.1 Configuration](#261-configuration)
         - [`.pre-commit-config.yaml` Configuration](#pre-commit-configyaml-configuration-1)
         - [Inline ignores](#inline-ignores)
+        - [The Dictionary](#the-dictionary)
   - [3. Development](#3-development)
     - [3.1 Testing](#31-testing)
       - [3.1.1 Testing scheme](#311-testing-scheme)
@@ -381,6 +382,11 @@ def initialise():  # pragma: no americanise
 ```
 
 
+##### The Dictionary
+
+The default dictionary is stored in `src/americanise_hook/americanise_dictionary.py`. To add words, please open an MR on this repo.
+
+
 ## 3. Development
 
 ### 3.1 Testing
diff --git a/src/americanise_hook/americanise.py b/src/americanise_hook/americanise.py
index 049d9a6..01545ec 100755
--- a/src/americanise_hook/americanise.py
+++ b/src/americanise_hook/americanise.py
@@ -15,54 +15,7 @@
 from typing import Union
 
 from src._shared import print_diff, resolvers
-
-DICTIONARY = {
-    # -se -> -ize
-    "characterise": "characterize",
-    "initialise": "initialize",
-    "instantiater": "instantiator",
-    "parametrise": "parametrize",
-    "prioritise": "prioritize",
-    "specialise": "specialize",
-    "organise": "organize",
-    # -yse -> -yze
-    "analyse": "analyze",
-    "catalyse": "catalyze",
-    # -our -> -or
-    "armour": "armor",
-    "behaviour": "behavior",
-    "colour": "color",
-    "flavour": "flavor",
-    "neighbour": "neighbor",
-    # -re -> -er
-    "centre": "center",
-    "fibre": "fiber",
-    "litre": "liter",
-    # -ae, -oe -> -e
-    "amoeba": "amoebae",
-    "anaesthesia": "anesthesia",
-    "caesium": "cesium",
-    # -ce -> -se
-    "defence": "defense",
-    # british uses "practice" as the noun and "practise" as the verb. US uses "practice" for both.
-    "practise": "practice",
-    # british uses "licence" as the noun and "license" as the verb. US uses "license" for both.
-    "licence": "license",
-    # -ge -> -g
-    "ageing": "aging",
-    "acknowledgement": "acknowledgment",
-    "judgement": "judgment",
-    # -ogue -> -og
-    "analogue": "analog",
-    "dialogue": "dialog",
-    # -l -> -ll
-    "fulfil": "fulfill",
-    "enrol": "enroll",
-    "skilful": "skillful",
-    # -ll -> -l
-    "labelled": "labeled",
-    "signalling": "signaling",
-}
+from src.americanise_hook.americanise_dictionary import DICTIONARY
 
 
 def _copy_case(target_string: str, input_string: str) -> str:
diff --git a/src/americanise_hook/americanise_dictionary.py b/src/americanise_hook/americanise_dictionary.py
new file mode 100644
index 0000000..3a13c24
--- /dev/null
+++ b/src/americanise_hook/americanise_dictionary.py
@@ -0,0 +1,51 @@
+# Copyright (c) 2025-2026 Benjamin Mummery
+
+"""The underlying dictionary for the Americanise hook."""
+
+DICTIONARY = {
+    # -se -> -ize
+    "characterise": "characterize",
+    "initialise": "initialize",
+    "instantiater": "instantiator",
+    "parametrise": "parametrize",
+    "prioritise": "prioritize",
+    "specialise": "specialize",
+    "organise": "organize",
+    # -yse -> -yze
+    "analyse": "analyze",
+    "catalyse": "catalyze",
+    # -our -> -or
+    "armour": "armor",
+    "behaviour": "behavior",
+    "colour": "color",
+    "flavour": "flavor",
+    "neighbour": "neighbor",
+    # -re -> -er
+    "centre": "center",
+    "fibre": "fiber",
+    "litre": "liter",
+    # -ae, -oe -> -e
+    "amoeba": "amoebae",
+    "anaesthesia": "anesthesia",
+    "caesium": "cesium",
+    # -ce -> -se
+    "defence": "defense",
+    # british uses "practice" as the noun and "practise" as the verb. US uses "practice" for both.
+    "practise": "practice",
+    # british uses "licence" as the noun and "license" as the verb. US uses "license" for both.
+    "licence": "license",
+    # -ge -> -g
+    "ageing": "aging",
+    "acknowledgement": "acknowledgment",
+    "judgement": "judgment",
+    # -ogue -> -og
+    "analogue": "analog",
+    "dialogue": "dialog",
+    # -l -> -ll
+    "fulfil": "fulfill",
+    "enrol": "enroll",
+    "skilful": "skillful",
+    # -ll -> -l
+    "labelled": "labeled",
+    "signalling": "signaling",
+}