diff --git a/docs/book/spell-check-custom-words.txt b/docs/book/spell-check-custom-words.txt
index 3b51147b9ee..69a868538f5 100644
--- a/docs/book/spell-check-custom-words.txt
+++ b/docs/book/spell-check-custom-words.txt
@@ -207,6 +207,7 @@ TicTacToe
 DAO
 Timelock
 transpiler
+Namespaces
 namespacing
 unsafety
 prioritizations