diff --git a/doc/designs/quic-design/glossary.md b/doc/designs/quic-design/glossary.md
index 818675a08a..a70cfd1ade 100644
--- a/doc/designs/quic-design/glossary.md
+++ b/doc/designs/quic-design/glossary.md
@@ -127,6 +127,10 @@ in which API calls can be made on different threads.
 **MSST:** Multi-stream single-thread. Refers to a type of multi-stream QUIC
 usage in which API calls must not be made concurrently.
 
+**ODCID:** Original Destination CID. This is the DCID found in the first Initial
+packet sent by a client, and is used to generate the secrets for encrypting
+Initial packets. It is only used temporarily.
+
 **PN:** Packet number. Most QUIC packet types have a packet number (PN); see RFC
 9000.