undershirt

noun

1. a collarless, usually pullover undergarment for the torso, usually of cotton and either sleeveless and low-cut or with sleeves, worn chiefly by men and children.

noun

1. mainly US and Canadian an undergarment worn under a blouse or shirtBrit name: vest

n.1640s, from under (adj.) + shirt (n.). Cf. North Frisian onnersjürt, Danish underskjorte.