knave / nāv/ • n. archaic a dishonest or unscrupulous man.DERIVATIVES: knav·er·y / -vərē/ n. (pl. -er·ies) .knav·ish adj.knav·ish·ly adv.knav·ish·ness n.ORIGIN: Old English cnafa ‘boy, servant’; related to German Knabe ‘boy.’

knave another term for the ‘jack’ in cards. The word originally (in Old English) meant ‘boy, servant’, and then generally someone of low social status; in Middle English, the sense of ‘dishonest or unscrupulous man’ developed. The playing-card sense is recorded from the middle of the 16th century.

knave †boy; †male servant OE.; base fellow XIII; lowest court card of a suit XVI. OE. cnafa = OHG. knabo (G. knabe boy) :- WGmc. *knaban-, rel. obscurely to synon. OE. cnapa = OS. cnapo, and OHG. knappo (G. knappe page, squire).
Hence knavery XVI, knavish XIV.