Plural of Knife

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The Quick Answer
The plural of knife is knives.

The Plural of Knife

The plural of knife is knives.
  • Great knives will enable you to cut precisely. Knife skills are essential in cooking. (Eric Ripert)
  • I've had people turn up to book signings with knives and guns. (Patricia Cornwell)
The noun knife 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 hero
zero
tomato		 add either s or es
(There are no rules for this - you have to know.)		 heroes
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 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

Why Is There Confusion over the Plural of Knife?

There is confusion because the rule for forming plurals with nouns ending in f or fe isn't straightforward. Most nouns will drop the f or fe and gain a ves. For example:
  • Wife becomes wives.
  • Leaf becomes leaves.
Some just add s. For example:
  • Safe becomes safes.
  • Chief becomes chiefs.
With some words, both versions are accepted. For example:
  • Scarf becomes scarfs or scarves.
  • Dwarf becomes dwarfs or dwarves.
The plural of knife is always knives. Unfortunately, there is no clever way of knowing which nouns ending f or fe follow which rules. You have to know.
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