Jack  —n. 1 device for raising heavy objects, esp. Vehicles. 2 court-card with a picture of a soldier, page, etc. 3 ship's flag, esp. Showing nationality. 4 device using a single-pronged plug to connect an electrical circuit. 5 small white target ball in bowls. 6 a = *jackstone. B (in pl.) Game of jackstones. 7 (jack) familiar form of john, esp. Typifying the common man, male animal, etc. (i'm all right, jack). —v. (usu. Foll. By up) 1 raise with or as with a jack (in sense 1). 2 colloq. Raise (e.g. Prices).  every man jack every person. Jack in slang abandon (an attempt etc.). [familiar form of the name john]