gig (n.1) Look up gig at Dictionary.com
"light, two-wheeled carriage, usually drawn by one horse" (1791), also "small boat," 1790, perhaps, on notion of bouncing, from Middle English ghyg "spinning top" (in whyrlegyg, mid-15c.), also "giddy girl" (early 13c., also giglet), from Old Norse geiga "turn sideways," or Danish gig "spinning top." Similar to words in continental Germanic for "fiddle" (such as German Geige); the connecting sense might be "rapid or whirling motion."
gig (n.2) Look up gig at Dictionary.com
"job," originally in the argot of jazz musicians, attested from 1915 but said to have been in use c.1905; of uncertain origin. As a verb, by 1939. Among the earlier meanings of gig was "combination of numbers in betting games" (1847). Related: Gigged; gigging.