"one who gads or walks idly about, especially from motives of curiosity or gossip" [Century Dictionary], 1830; see gad (v.) + about (adv.). As an adjective from 1817. Verbal phrase gadder about is attested from 1560s.
gaberdine
gabfest
gable
Gabriel
gad
gadabout
Gadarene swine
gadfly
gadget
Gadhelic
gadolinium