Definify.com
Webster 1913 Edition
Watchword
Watch′wordˊ
,Noun.
 1. 
A word given to sentinels, and to such as have occasion to visit the guards, used as a signal by which a friend is known from an enemy, or a person who has a right to pass the watch from one who has not; a countersign; a password. 
2. 
A sentiment or motto; esp., one used as a rallying cry or a signal for action. 
Nor deal in 
watchwords 
overmuch. Tennyson.
Webster 1828 Edition
Watchword
WATCHWORD
,Noun.
 Definition 2025
watchword
watchword
English
Noun
watchword (plural watchwords)
- a prearranged reply to the challenge of a sentry or a guard; a password or signal by which friends can be known from enemies
 -  a word used as a motto, as expressive of a principle or rule of action; a maxim, byword
-  1919, Boris Sidis, The Source and Aim of Human Progress:
- Atrocities of the most vicious kind were justified by the watchwords: "This is war!" "Might is Right." "Necessity knows no law."
 
 
 -  1919, Boris Sidis, The Source and Aim of Human Progress:
 - a rallying cry
 
Translations
a prearranged reply to the challenge of a sentry or a guard
word used as expressive of a principle
rallying cry
See also
References
- watchword in The Century Dictionary, The Century Co., New York, 1911