Plural of Tooth

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The Quick Answer
The plural of tooth is teeth.

The Plural of Tooth

The plural of tooth is teeth.
  • Sharks grow a new set of teeth every two weeks to replace worn teeth.
  • I told my dentist my teeth are going yellow. he told me to wear a brown tie. (Rodney Dangerfield)
Some words do not form their plurals by adding 's' to the end but by changing their forms (e.g., man becomes men, foot becomes feet, mouse becomes mice).

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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 cat
scythe		 add s cats
scythes
Noun Ending s, sh, ch, x or z bus
dress		 add es buses
dresses
Nouns ending [consonant] o mango
zero
tomato		 add either s or es
(There are no rules for this - you have to know.)		 mangoes or mangos
zeros
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 tooth
louse 		some nouns undergo a vowel or letters change teeth
lice
More exceptions salmon
sheep 		some nouns do not change at all salmon
sheep

Why Is There Confusion over the Plural of Tooth?

There is confusion because the plural of tooth is not formed by adding 's' but by changing its central vowel. Several other words form their plurals in this way. There is no rule to remember them. They have to be memorized.
Another Interactive Exercise
Here are three randomly selected questions from another exercise on plurals, which can be edited, printed to create an exercise worksheet, or sent via email to friends or students.

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See Also

Unusual pluralsPlural forming table Quirks with forming plurals Forming the plurals of abbreviations Forming the plurals of compound nouns