Dab
Middle English: symbolic of a light striking movement; compare with dabble and dib.
wiktionary
From Middle English dabben(“to strike”), perhaps ultimately imitative. [1] Comparable with Middle Dutch dabben(“to pinch, knead, fumble, dabble”) (Dutch dabben(“(of a horse) to stamp with the forelegs”)), Dutch deppen(“to dab”), possibly German tappen(“to fumble, grope”).
The noun is from Middle English dabbe(“a strike, blow”), from the verb. Related to tap. Compare also drub, dub.
African-American sense of “playful box” perhaps influenced by dap(“fistbump”).
Perhaps corrupted from adept.
Late Middle English dabbe, of unknown origin; perhaps related to sense 1(“to press against lightly”) as in "a soft mass dabbed down." [2]
Back slang for bad.
etymonline
dab (v.)
early 14c., dabben "to strike," of unknown origin, perhaps imitative. Compare Old Norse dabba "to tap, slap." Modern sense of "strike gently with the hand, strike with a slight, quick pressure" developed by mid-16c., influenced by French dauber (see daub). Related: Dabbed; dabbing; dabber.
As a noun from c. 1300, "heavy blow with a weapon," later "gentle blow with the hand or some soft substance" (1755). Meaning "small lump or mass of something soft" is from 1749. Dab hand is British slang, 1828, from dab "expert, knowing or skillful person" (1690s), said by OED to be "school slang," of unknown origin, perhaps from dab in the "strike lightly" sense. Compare dabster, which meant both "an expert" (1708) or "a bungler" (1871, perhaps by confusion with daub).
