n.pl. (US pajamas) 1 a suit of loose trousers and jacket for sleeping in. 2 loose trousers tied round the waist, worn by both sexes in some Asian countries. 3 (pyjama) (attrib.) designating parts of a suit of pyjamas (pyjama jacket; pyjama trousers). Etymology: Urdu pa(e)jama f. Pers. pae, pay leg + Hindi jama clothing
Pyjamas Py*ja"mas, or, chiefly U. S., Pajamas Pa*ja"mas, n. pl. 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.
Note: 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.N-PLURAL: also apairof N