Shirt

n. garment with long or short sleeves that is worn on the upper body

In American English, shirt can refer to almost any upper-body garment other than coats and bras (the term "top" is sometimes used in ladieswear). In British English, a shirt is more specifically a garment with a collar, cuffs, and a full vertical opening with buttons; what is known in American English as a dress shirt.
See more at Wikipedia.org...

Noun
1. a garment worn on the upper half of the body
(hypernym) garment
(hyponym) camise
(substance-meronym) shirting
(part-meronym) dickey, dickie, dicky, shirtfront
Verb
1. put a shirt on
(hypernym) dress, clothe, enclothe, garb, raiment, tog, garment, habilitate, fit out, apparel

n. shirt, garment worn on the upper body

n. undershirt