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c.1847, short for Zoological Gardens of the London Zoological Society, established 1828 in Regent's Park to house the society's collection of wild animals. From comb. form of Greek zoion "an animal," literally "a living being," from PIE root *gwei- "to live, life" (cf. Greek bios "life," Old English cwicu "living;" see bio-). Slang meaning "crowded and chaotic place" first recorded 1935.
zoo- or zo-
Animal; animal kingdom: zoonosis.
[echoic of a heavy blow; a 1929 Bookman article on sound effects is entitled ''Socko, Whamo, and Sonk!'']