watchword

A watchword is a word or short phrase used as a signal of identity, a password, or a guiding principle. In security contexts, a watchword proves authorization; more broadly, it can serve as a motto or slogan for a group.

Historically, watchwords were spoken at guard posts or during operations to identify friends from foes. A sentinel would verify the word before granting passage or trust.

The term combines watch and word, reflecting its origin in guarding and monitoring activities. It dates from English usage and has long appeared in military and security contexts.

In contemporary language, watchword often denotes a guiding principle or policy emphasis, such as "efficiency" or "security" being the watchword of a program. In this sense, it is often used metaphorically rather than as a literal password.

Related terms include motto, slogan, and password. While closely related, a watchword in everyday use highlights a core objective that shapes behavior rather than simply providing entry.