watchword
1. [ noun ] a slogan used to rally support for a cause
Synonyms: cry rallying_cry battle_cry war_cry
Examples:

"a cry to arms" "our watchword will be `democracy'"

Related terms: motto
2. [ noun ] a secret word or phrase known only to a restricted group
Synonyms: word countersign parole password
Examples:

"he forgot the password"

Related terms: positive_identification secret
Similar spelling:   watcher
  Wadsworth