undershirt

thumb|240px|Example of a T-shirt to be worn as an undershirt and usually not as outerwear An undershirt in American English, vest in British and South African English, baniyan in the Indian subcontinent, or singlet in Australia and New Zealand, is an article of underwear worn underneath a shirt for warmth or to protect it from body sweat and odors. It can have short sleeves (T-shirt) or be sleeveless (A-shirt).

An undershirt may be worn to protect the body from stiff or otherwise uncomfortable fabric. It also makes dress shirts less transparent, and absorbs sweat that would otherwise wet the shirt's fabric. It can be worn during winter months as an extra layer of warmth, and reduces wear on the upper layers of clothing.