1. A conceited or impudent person.
2. A mischievous child.
3. Archaic A monkey or an ape.
[From Middle English Jack Napis, nickname of William de la Pole, Fourth Earl and First Duke of Suffolk (1396-1450), probably ultimately from alteration of ape, monkey, ape (because his coat of arms depicted a chain and clog of the kind used to tether a pet monkey).]
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