The spelling pajamas is used in American English. The forms pyjama and pajama are used as modifiers. A pair of pyjamas consists of loose trousers and a loose jacket that people, especially men, wear in bed. My brother was still in his pyjamas. a pyjama jacket
A garment, similar to the Oriental pyjama (which see), adopted among Europeans, Americans, and other Occidentals, for wear in the dressing room and during sleep; also, a suit of drawers and blouse for such wear
Clothes for wearing to bed and sleeping in, usually consisting of a loose-fitting jacket and trousers