diff --git a/changelogs/appendices/newsfragments/1468.clarification b/changelogs/appendices/newsfragments/1468.clarification
new file mode 100644
index 00000000..6f8ab86f
--- /dev/null
+++ b/changelogs/appendices/newsfragments/1468.clarification
@@ -0,0 +1 @@
+Clarify that the term "Canonical JSON" is a specific thing within the matrix specification.
diff --git a/content/appendices.md b/content/appendices.md
index dc3ced66..446e709a 100644
--- a/content/appendices.md
+++ b/content/appendices.md
@@ -83,7 +83,11 @@ object.
 
 ### Canonical JSON
 
-We define the canonical JSON encoding for a value to be the shortest
+To ensure that all implementations use the same JSON encoding we define
+"Canonical JSON". This should not be confused with other uses of
+"Canonical JSON" outside of the specification.
+
+We define this encoding for a value to be the shortest
 UTF-8 JSON encoding with dictionary keys lexicographically sorted by
 Unicode codepoint. Numbers in the JSON must be integers in the range
 `[-(2**53)+1, (2**53)-1]`.