In communication, a code word is an element of a standardized code or protocol. Each code word is assembled in accordance with the specific rules of the code and assigned a unique meaning. Code words are typically used for reasons of reliability, clarity, brevity, or secrecy.

A code name or cryptonym is a word or name used, sometimes clandestinely, to refer to another name, word, project or person. Names are often used for military purposes, or in espionage. They may also be used in industrial counter-industrial espionage to protect secret projects and the like from business rivals, or to give names to projects whose marketing name has not yet been determined. Another reason for the use of names and phrases in the military is that they transmit with a lower level of cumulative errors over a walkie-talkie or radio link than actual names.