singlet
noun [ C ] uk/ˈsɪŋ.ɡlət/ us/ˈsɪŋ.ɡlət/
mainly UK背心;无袖运动衫
a piece of clothing without sleeves that is worn on the top part of the body under clothes, or for playing particular sports
Australian English（通常无袖）内上衣
a type of underwear, often with no sleeves, that covers the upper part of the body and is worn for extra warmth
Compare: vest noun