diff --git a/meta/acronyms.txt b/meta/acronyms.txt
index c960e4ced..fc2649a4b 100644
--- a/meta/acronyms.txt
+++ b/meta/acronyms.txt
@@ -1,4 +1,5 @@
 # this file defines acronyms, one acronym per line
+ACK - Acknowledgement
 ACL - Access Control List
 AES - Advanced Encryption Standard
 AN - Association Number