diff --git a/Spelling.md b/Spelling.md
index d6c45795..31b738bf 100644
--- a/Spelling.md
+++ b/Spelling.md
@@ -5,7 +5,7 @@ This page is a statement of policy. Do not edit it without approval/discussion.
 Policy:
 
 * American spellings over British spellings
-* **iff** means "if or only iff" (https://en.wiktionary.org/wiki/iff), but we don't use it in public-facing docs (not if it'd show up in exported identifiers in godoc)
+* **iff** means "if and only if" (https://en.wiktionary.org/wiki/iff), but we don't use it in public-facing docs (not if it'd show up in exported identifiers in godoc)
 * avoid Latin abbreviations in godoc
 * use **cancellation** (two ells), not cancelation. See https://golang.org/cl/170060
 * use **canceled** (one ell), not cancelled.