motto

(heraldry) A sentence, phrase, or word, forming part of an heraldic achievement.

A sentence, phrase, or word, prefixed to an essay, discourse, chapter, canto, or the like, suggestive of its subject matter; a short, suggestive expression of a guiding principle; a maxim.

(obsolete) A paper packet containing a sweetmeat, cracker, etc., together with a scrap of paper bearing a motto.