(slang, derogatory) Jack in the Box (the chain of fast food restaurants).

plural of Jack Sprat

(informal) A small or skinny boy or man.

Alternative form of supplejack

Alternative form of supplejack

(UK, slang, obsolete) An attendant at the watermen's stairs on the river and seaport towns.

plural of Jack-in-the-water

(construction) A telescoping steel post used for the temporary support of ceilings, walls, and trenches.

plural of jack post

A jack (used to lift up a vehicle)