boxer shorts 
(also boxers)
plural noun
Men’s loose underpants similar in shape to the shorts worn by boxers.You get the loose mesh boxer shorts and thong underwear for one price....
- It will be more comfortable to wear loose clothing such as boxer shorts or a dressing gown with no underpants or trousers until the wound has healed.
- Loose boxer shorts are also considered passé, although they have improved over the years.