1. a name assigned to conceal the real identity of a person, as a spy, or to conceal the existence or purpose of a plan, military operation, etc.
2. Also called code' phrase". a word or phrase assigned a meaning understood only by those who are secretly informed of it.
Pronunciation: (kōd'nām"), [key]
—v.t., -named, -nam•ing.
to assign a code name to.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.