Document the use of attr_list with def_list.

docs/changelog.md

@@ -32,6 +32,7 @@ See the [Contributing Guide](contributing.md) for details.
 * Fix quadratic-time regex backtracking in `ReferenceProcessor` when a link
   reference definition has no URL, e.g. a line consisting only of `[id]:`
   followed by many trailing spaces (#798).
+* Document `attr_list` usage for `def_list` (#1123).
 
 ## [3.10.3] - 2026-07-30
 

docs/extensions/attr_list.md

@@ -111,6 +111,23 @@ A setext style header { #setext}
 ### A hash style header ### { #hash }
 ```
 
+Similarly, when using with the [Definition List] Extension, an attribute list
+must be on the same line as the term.
+
+``` md-render
+---
+extensions: [attr_list, def_list]
+---
+Apple { #apple }
+:   Pomaceous fruit of plants of the genus Malus in
+    the family Rosaceae.
+
+Orange { #orange }
+:   The fruit of an evergreen tree of the genus Citrus.
+```
+
+[Definition List]: ./definition_lists.md
+
 !!! seealso "See Also"
 
     By default, the [Fenced Code Blocks](./fenced_code_blocks.md#attributes) extension includes limited support for