Pajamas, also spelled pyjamas (see also spelling differences), can refer to several related types of clothing
Clothing refers to any covering for the human body that is worn. The wearing of clothing is exclusively a human characteristic and is a feature of nearly all human societies...

. The original paijama are loose, lightweight trousers
Trousers are an item of clothing worn on the lower part of the body from the waist to the ankles, covering both legs separately...

 fitted with drawstring
A drawstring is a string, cord, or rope used to "draw" or tie closed an opening in fabric or other material...

 waistbands and worn in South
South Asia
South Asia, also known as Southern Asia, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities , also includes the adjoining countries to the west and the east...

 and West Asia by both sexes. In many English
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...

-speaking nations, pajamas are loose-fitting, two-piece garments derived from the original garment and worn chiefly for sleeping
Nightwear, also called "sleepwear", "sleeping suit", "nightclothes", or "nightdress", is clothing designed to be worn while sleeping. The style of nightwear worn may vary with the seasons, with eg. warmer styles being worn in colder conditions...

, but sometimes also for lounging, also by both sexes.