Definition of "Jack" :

noun: male donkey

noun: any of several fast-swimming predacious fishes of tropical to warm temperate seas

noun: tool for exerting pressure or lifting

noun: one of four face cards in a deck bearing a picture of a young prince

noun: small flag indicating a ship's nationality

noun: game equipment consisting of one of several small six-pointed metal pieces that are picked up while bouncing a ball in the game of jacks

noun: an electrical device consisting of a connector socket designed for the insertion of a plug

noun: a small ball at which players aim in lawn bowling

noun: immense East Indian fruit resembling breadfruit; it contains an edible pulp and nutritious seeds that are commonly roasted

noun: someone who works with their hands; someone engaged in manual labor

noun: a man who serves as a sailor

noun: a small worthless amount

"You don't know jack."

verb: hunt with a jacklight

verb: lift with a special device

"Jack up the car so you can change the tire."