jack Noun A mechanical device used to raise and (temporarily) support a heavy object.
jack Noun A man or men in general.
jack Noun A male animal.
jack Noun The card ranking between the and of any suit, picturing a knave or prince on its face. In some card games has a value of eleven based on its rank, but in many card games has a value of ten like the "ten", "queen", and cards. Also called a "knave".
jack Noun A knave (a servant or later, a deceitful man).
jack Noun A male ass.
jack Noun A surface-mounted connector for electrical, especially telecommunications, equipment.
jack Noun A target ball in bowls, etc; a jack-ball.
jack Noun A small, six-pointed playing piece used in the game of jacks.
jack Noun Nothing, jackshit.
jack Noun A small flag at the bow of a ship.
jack Noun A naval ensign flag flown from the main mast, mizzen mast, or the aft-most major mast of (especially) British sailing warships; Union Jack.
jack Noun A coarse and cheap medieval coat of defense, especially one made of leather.
jack Noun A penny with a head on both sides, used for cheating. (Reference: Sidney J. Baker, "The Australian Language", second edition, 1966, chapter XI section 3, page 243.)
jack Noun Money.
jack Noun A smooth often ovoid large gravel or small cobble in a natural water course.
jack Noun A common name for the freshwater pike, green pike or pickerel.
jack Noun Large California rockfish.
jack Noun An order of marine fish in the "Carangidae" family.
jack Noun A sailor; a "jack tar".
jack Verb To use a jack.
jack Verb To steal something, typically an automobile.
jack Verb To raise or increase.
jack Verb To hit (the ball) hard; especially, to hit (the ball) out of the field, producing a home run.