from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A pullover sport shirt of knitted cotton.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A casual top with buttons and a protruding collar.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a shirt with short sleeves designed for comfort and casual wear
From polo + shirt; so called because they were initially modeled on the type worn by polo players. (Wiktionary)