Emily Dickinson Lexicon

GAB, n. [Scot. gab, Dan. gab, the mouth, and a gap or gaping; Sw. gap; Russ. guba, a lip, a bay or gulf, the mouth of a river; Ir. cab, the mouth; connected probably with gabble, giberish, Sax. gabban, to mock, perhaps to make mouths. See Gabble and Gape.]

The mouth; as in the phrase, the gift of the gab, that is, loquaciousness. But the word is so vulgar as rarely to be used.