Longman Dictionary of Contemporary English
n. underpants, type of underwear worn in skin contact with the hip portion of the body, small enough to be worn invisibly under shorts.
Usage examples of "undershorts".
Obie was still bleeding slightly from a cut below his eye, but Demmy had torn a strip off his undershorts for a bandage—wearing human-type clothing had its uses, after all—and the whole cohort looked presentable enough as they lined up before the six huge Major Seniors.
He was jailing, jeans at low tide in that cool lockup look of six inches of pastel undershorts showing.
The regimental sergeant major sloshed past me dressed only in a pair of green undershorts and carrying a Thompson submachine gun in one hand.
Lean fingers unbuckled his belt, unzipped his fly, hooked in the waistbands of both trousers and undershorts and pushed them down.