knave

Concise Oxford English Dictionary © 2008 Oxford University Press:
knave/neɪv/

▶noun

• 1 archaic a dishonest or unscrupulous man.

• 2 (in cards) a jack.

– derivatives
knavery noun (pl. knaveries),
knavish adjective,
knavishly adverb,
knavishness noun.

– origin OE cnafa ‘boy, servant’, of W. Gmc origin.