Meaning
To boast; to display one's actions, merits or advantages ostentatiously; to tell boastful stories; followed by of; as, to brag of a good horse, or of a feat.
To brag on is vulgar; indeed the word itself is become low, and is not to be used in elegant composition.
BRAG, n. A boast, or boasting; ostentatious verbal display of one's deeds, or advantages; the thing boasted.
Spenser has used this word as an adverb for proudly.
BRAG, n. A game at cards.