Pyjamas, or pajamas (American English), often shortened to PJs, jimmies, jimjams or jammies, can refer to several related types of clothing. Pajamas are loose-fitting, two-piece garments derived from the original garment and worn chiefly for sleeping, but sometimes also for lounging, also by both sexes. More generally, pajamas may refer to several garments, for both daywear and nightwear, derived from traditional pajamas and involving variations of style and material.