<p><strong>noun</strong></p><ul><li>any of various portable devices for raising or lifting heavy objects short heights, using various mechanical, pneumatic, or hydraulic methods.</li><li>a playing card bearing the picture of a soldier or servant.</li><li>a connecting device in an electrical circuit designed for the insertion of a plug.</li><li>Informal. fellow; buddy; man (usually used in addressing a stranger).</li><li>one of a set of small metal objects having six prongs, used in the game of jacks.</li><li>one of any other set of objects, as pebbles, stones, etc., used in the game of jacks.</li><li>jacks, (used with a singular verb) a children’s game in which small metal objects, stones, pebbles, or the like, are tossed, caught, and moved on the ground in a number of prescribed ways, usually while bouncing a rubber ball.</li><li>any of several carangid fishes, especially of the genus <em>Caranx</em>, as <em>C. hippos</em> crevalle jack, or jack crevalle, of the western Atlantic Ocean.</li><li>Slang. money.</li><li>Slang: Vulgar. jack shit.</li><li>a small flag flown at the jack staff of a ship, bearing a distinctive design usually symbolizing the nationality of the vessel.</li><li>either of a pair of crosstrees at the head of a topgallant mast, used to hold royal shrouds away from the mast.</li><li>a sailor.</li><li>a device for turning a spit.</li><li>a small wooden rod in the mechanism of a harpsichord, spinet, or virginal that rises when the key is depressed and causes the attached plectrum to strike the string.</li><li>a small, usually white bowl or ball used as a mark for the bowlers to aim at.</li><li>a mechanical figure that strikes a clock bell.</li><li>a premigratory young male salmon.</li><li>the male of a kestrel, hobby, or especially of a merlin.</li></ul><p><strong>verb (used with object)</strong></p><ul><li>to lift or move (something) with or as if with a jack (usually followed by up).</li><li>Informal. to increase, raise, or accelerate (prices, wages, speed, etc.) (usually followed by up).</li><li>Informal. to boost the morale of; encourage (usually followed by up).</li><li>Slang. to mess up, ruin, or injure (usually followed by up).</li><li>to jacklight.</li></ul><p><strong>verb (used without object)</strong></p><ul><li>to jacklight.</li></ul><p><strong>adjective</strong></p><ul><li>Carpentry. having a height or length less than that of most of the others in a structure; cripple.</li></ul><p><strong>verb phrase</strong></p><ul><li>Slang. to give oneself an injection of a controlled substance.</li></ul>