[ zoo ]
/ zu /
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noun, plural zoos.
Also called zoological garden. a parklike area in which live animals are kept in cages or large enclosures for public exhibition.
Informal. a place, activity, or group marked by chaos or unrestrained behavior.
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Origin of zoo

First recorded in 1840–50; first two syllables of zoological garden taken as one syllable

Other definitions for zoo (2 of 2)


a combining form meaning “living being,” “animal,” used in the formation of compound words: zoometry; zooplankton.
Also especially before a vowel, zo-.

Origin of zoo-

Combining form representing Greek zôion animal
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What does zoo- mean?

The combining form zoo– is used like a prefix meaning “living being” or “animal.” It is often used in scientific terms, especially in biology.

The form zoo– comes from Greek zôion, meaning “animal.”

What are variants of zoo-?

When combined with words or word elements that begin with a vowel, zoo– becomes zo, as in zooid.

When combined as a suffix, zoo– becomes zoa or zoon, as in protozoa or ectozoon. Want to know more? Read our Words That Use articles for zo-, -zoa, and -zoon.

Examples of zoo-

An example of a word you may have encountered that features zoo– is zoology, “the science or branch of biology dealing with animals.”

We know zoo– means “animal,” and the logy portion of the word refers to “science,” from Greek logía. Zoology literally translates to “animal science.”

The word zoo is ultimately shortened from zoological garden; zoological is the adjective form of zoology.

What are some words that use the combining form zoo-?

What are some other forms that zoo– may be commonly confused with?

Not every word that begins with the exact letters zoo– or zo-, such as zoom or zooty, is necessarily using either combining form to denote “animal.” Learn why zooty means “flamboyant” at our entry for the word.

Break it down!

The combining form metry means “the process of measuring.” With this in mind, what is zoometry?

How to use zoo in a sentence

British Dictionary definitions for zoo (1 of 2)

/ (zuː) /

noun plural zoos
a place where live animals are kept, studied, bred, and exhibited to the publicFormal term: zoological garden

Word Origin for zoo

C19: shortened from zoological gardens (originally applied to those in London)

British Dictionary definitions for zoo (2 of 2)


before a vowel zo-

combining form
indicating animalszooplankton

Word Origin for zoo-

from Greek zōion animal
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Idioms and Phrases with zoo


see it's a zoo.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.