mid-13c., from O.Fr. signifier (12c.), from L. significare "to show by signs, mean, signify," from significus (adj.), from signum "sign" (see sign (n.)) + root of facere "to make" (see factitious). Intrans. sense of "to be of importance" is
attested from 1660s. Meaning "engage in mock-hostile banter" is Amer.Eng. black slang first recorded 1932.
"...'signifying,' which in Harlemese means making a series of oblique remarks apparently addressed to no one in particular, but unmistakable in intention in such a close-knit circle." ["Down Beat," March 7, 1968]