From waist + coat.

• (spelling pronunciation) enPR: wās(t)'-kōt, IPA: /ˈweɪs(t)kəʊt/
• (dated) enPR: wĕs'kət, IPA: /ˈwɛskət/

waistcoat (plural waistcoats)

1. An ornamental garment worn under a doublet.
2. (chiefly, British) A sleeveless, collarless garment worn over a shirt and under a suit jacket.

   Synonyms: vest

   Coordinate term: gilet

   • 1897 December (indicated as 1898), Winston Churchill, chapter II, in The Celebrity: An Episode, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., Ltd., →OCLC ↗:

     Sunning himself on the board steps, I saw for the first time Mr. Farquhar Fenelon Cooke. […] A silver snaffle on a heavy leather watch guard which connected the pockets of his corduroy waistcoat, together with a huge gold stirrup in his Ascot tie, sufficiently proclaimed his tastes.

• French: gilet
• German: Weste, (regional, obsolescent) Gilet
• Italian: panciotto, gilè, corpetto
• Portuguese: colete
• Russian: жиле́т
• Spanish: chaleco, chalequillo