undershirt
- A piece of underwear worn under a shirt, typically a lightweight, sleeveless garment that provides an extra layer of warmth or absorbs sweat. nounHe wore an undershirt beneath his dress shirt to stay warm.She bought a pack of cotton undershirts for her son to wear to school.
- A sleeveless or short-sleeved shirt worn as an outer garment, often in a casual setting. nounDuring the summer, he often wears an undershirt with shorts.The undershirt was comfortable enough to wear on its own during the hot day.