My grandfather has always liked wearing a vest.
My grandfather used to wear a waistcoat under his suit.
暑くなったのでチョッキを脱いだ。
It got hot, so I took off my vest.
bulletproof vest
Loanword from Portuguese 'jaqueta' or possibly English 'jacket', entering Japanese in the late Edo or early Meiji period. The exact derivation is uncertain.