Motto \Mot"to\, n.; pl. Mottoes. [It. motto a word, a saying, L. muttum a mutter, a grunt, cf. muttire, mutire, to mutter, mumble; prob. of imitative origin. Cf. Mot a word.]

1. (Her.) A sentence, phrase, or word, forming part of an heraldic achievment.

2. 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.

It was the motto of a bishop eminent for his piety and good works, . . . ``Serve God, and be cheerful.'' --Addison.

Source: Webster's Revised Unabridged Dictionary (1913)