Grammar Monster
Grammar Monster

Plural of Louse

The Quick Answer
The plural of louse is lice.

The Plural of Louse

The plural of louse is lice.
  • Lice spread diseases such as typhus.
  • Lice cannot survive for long if removed from their host.
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, tooth becomes teeth).

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 louse
tooth
some nouns undergo a vowel or letters change lice
teeth
More exceptions salmon
sheep
some nouns do not change at all salmon
sheep

Why Is There Confusion over the Plural of Louse?

There is confusion because the plural of louse 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.