early 14c., "bag for carrying things," especially (late 14c.) "small bag in which money is carried," from Anglo-French puche, Old North French pouche (13c.), Old French poche "purse, poke," all from a Germanic source (cf. Old English pocca "bag;" see poke (n.1)). Extended to cavities in animal bodies from c.1400.
A pocketlike space in the body.