Green’s Dictionary of Slang

zoot suit n.

also zoot
[? New Orleans patois zoot, cute]

1. [1940s+] (orig. US black) a style of suit worn in the 1940s and 1950s, characterized by a long, draped jacket with padded shoulders and high-waisted tapering trousers; also attrib.; thus zoot-suited adj.; zoot-shirt, a brightly coloured shirt designed to be worn with a zoot suit; zoot pants, trousers designed like those of a zoot suit; zoot suit action, a fashion competition in which a wearer of a zoot suit attempts to outdo their rivals.

2. [1930s–40s] (US black) overexaggerated clothes.

3. [1970s+] (UK prison) prison clothing worn in the punishment cell.

In derivatives

zoot-suiter (n.) (also zooter, zoot suit) [1930s–60s] (US)

1. a wearer of a zoot-suit, thus a fashionable person.

2. in derog. use, a foolish, arrogant, vulgar young man, esp. when his image is boosted by flashy clothes.

zoot-suity (adj.)

affecting the styles associated with wearers of zoot suits.

In phrases

zooted up (adj.)

[1940s] (US) wearing a zoot suit.