n. an upper undergarment with no collar, and with short or no sleeves, worn next to the skin under a shirt; a singlet or (British) a vest
the GNU version of the Collaborative International Dictionary of English
n. A shirt worn next the skin, under another shirt; -- called also undervest.
The Century Dictionary and Cyclopedia
n. A shirt or similar garment, as of woolen, worn under a shirt and next to the skin.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a collarless men's undergarment for the upper part of the body
Word Usage
"Listen, I'm looking at this photo of Ripley in her underwear, from the original -- the undershirt is the same, but these briefs -- I think maybe they aren't really women's briefs, I think these are men's, like a Speedo version of undies."