Plural of Zoo

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The Plural of Zoo

The plural of zoo is zoos.

• In the 1970s, zoos began making conservation their central role.
• Many of today's zoos hope to stop or slow the decline of many endangered species.

The noun zoo adheres to the standard rules for forming the plurals of nouns in English (shown in the table below).

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The Standard Rules for Forming the Plurals

The table below shows the standard rules for forming the plurals of nouns in English.

Type	Example of Type	Forming the Plural	Plural
Most Nouns	lamp scythe	add s	lamps scythes
Noun Ending s, sh, ch, x or z	bus dress	add es	buses dresses
Nouns ending [consonant] o	zoo tomato	add either s or es (There are no rules for this - you have to know.)	zoos tomatoes
Nouns ending [vowel] o	patio ratio	add s	patios ratios
Nouns ending [consonant] y	story penny	change the y to an i and add es	stories pennies
Nouns ending [vowel] y	storey () donkey	add s	storeys donkeys
Nouns ending f or fe	dwarf knife	ves and/or s (There are no rules - you have to know.)	dwarfs knives
Exceptions	man louse	some nouns undergo a vowel or letters change	men lice
More exceptions	salmon sheep	some nouns do not change at all	salmon sheep

Read more about English spelling rules.

Why Is There Confusion over the Plural of Zoo?

There is confusion because the rule for forming plurals with nouns ending in o isn't straightforward. Most nouns will just add an s. For example:

• Kangaroo becomes kangaroos.
• Piano becomes pianos.

Some add es. For example:

• Echo becomes echoes.
• Torpedo becomes torpedoes.

With some words, both versions are accepted. For example:

• Volcano becomes volcanoes or volcanos.
• Halo becomes haloes or halos.

The plural of zoo is always zoos. Unfortunately, there is no clever way of knowing which nouns ending o follow which rules. You have to know. (For example, you have to know that zoo becomes zoos, but hero becomes heroes.)

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