From Middle English gabben, from Old English gabban (“to scoff, mock, delude, jest”) and Old Norse gabba (“to mock, make sport of”); both from Proto-Germanic *gabbanan (“to mock, jest”), from Proto-Indo-European *ghabh- (“to be split, be forked, gape”). Cognate with Scots gab (“to mock, prate”), North Frisian gabben (“to jest, sport”), Middle Dutch gabben (“to mock”), Middle Low German gabben (“to jest, have fun”).
gab (plural gabs)
Usage notes 
Gab in the sense "mouth as gob" was used to specifically describe the open-forked ends of rods controlling reversing early steam engines.
- See also Wikisaurus:talkative
Derived terms 
- (intransitive, obsolete) To jest; to tell lies in jest; exaggerate; lie.
- (intransitive) To talk or chatter a lot, usually on trivial subjects.
- (transitive, obsolete) To speak or tell falsely.
- a large dove
gab n (singular definite gabet, plural indefinite gab)