From Longman Dictionary of Contemporary Englishjackjack1 /dʒæk/ noun [countable] 1 TZa piece of equipment used to lift a heavy weight off the ground, such as a car, and support it while it is in the air a hydraulic jack2 DGCa card used in card games that has a man’s picture on it and is worth less than a queen and more than a tenjack of hearts/clubs etc a pair of jacks3 Tan electronic connection for a telephone or other electric machine a phone jack4 a) jacks [plural]DG a children’s game in which the players try to pick up small objects called jacks while bouncing and catching a ball b) DGa small metal or plastic object that has six points, used in this game5 DSOa small white ball at which players aim larger balls in the game of bowls6 → jack (shit) → jumping jack, Union Jack
Examples from the Corpus
jack• Twin motor jack on stabilizer for pitch trim.• He put his finger in the jack of the outlet.• Iain, skipping his father, then extricated them by trailing the jack and adding perfect drawing shots to collect a four.jack of hearts/clubs etc• East then found the inspired opening lead of the jack of hearts.jackjack2 verb → jack somebody around → jack something ↔ in → jack off → jack something ↔ up→ See Verb tableExamples from the Corpus
jack• So I couldn't jack it in when things were going well.• We've come to tell you to jack it in.• We were always putting pressure on him to jack it in.• But they are not mere company drones used only to jack up corporate profits.• Ever since Congress decided to jack up the price of sugar.• By jacking up the price of the cheapest disposal route, a landfill tax makes other options look more attractive.• For the first time in years, there were no stadium tours to jack up the year-end grosses.Origin jack1 (1300-1400) From the man's name Jack 