Examples from the Web for undershirt
Humiliatingly, the president is shown in his undershirt, wiping off sweat with a towel.
Flat on the floor, where the light of the lamp fell on his face, lay a man dressed only in his trousers and undershirt.The Underdog|F. Hopkinson Smith
Yes; over the gelatin we had clothing; had a suit, shirt and undershirt, and underneath that a clipped goatskin.Warren Commission (5 of 26): Hearings Vol. V (of 15)|The President's Commission on the Assassination of President Kennedy
Spots of blood were also noticed on the right sleeve of the prisoner's undershirt.