noun
Refers to a garment worn next to the skin under outer clothing; can be a shirt-like undergarment. The term is somewhat formal or literary; in everyday speech, 下着 (したぎ) is more common.
彼は襯衣を着替えた。
He changed his underwear.
この襯衣は肌触りが良い。
This undershirt feels good against the skin.