dab

dab · verb, noun, adverb¹

1. Middle English · inherited fromdabbe“a strike, blow”
2. Middle English · inherited fromdabben“to strike”
3. English todaydab

From Middle English dabben (“to strike”), probably of North Germanic origin, related to Old Icelandic dabba (“to tap, slap”), perhaps ultimately imitative. Compare also 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”).

dab · noun²

Unknown. First use in print was in 1691, in The Athenian Mercury; it is also found in the Dictionary of the Canting Crew of 1698; see quotations for both. Originally used in the cant of criminals, and later in school slang. It may be a profound alteration of adept, likely from deliberate slangy usage thereof (rather than natural sound-change), which if true would give such earlier forms as *adep (or *dept) > *dep > *deb.

dab · noun³

1. Middle English · inherited fromdabbe
2. English todaydab

Late Middle English dabbe, of unknown origin; perhaps related to sense 1 (“to press against lightly”) as in "a soft mass dabbed down."

dab · adjective⁴

Back slang for bad.