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Plural of Virus

What Is the Plural of Virus?

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The Quick Answer

The plural of "virus" is "viruses."
The plural of "virus" is "viruses."
  • Viruses are found in almost every ecosystem on Earth. correct tick
  • Viruses are considered by some to be a life form, because they carry genetic material and can reproduce. correct tick
The noun "virus" has a Latin root, but is one of the few nouns that has no plural in Latin. It occurs only in the singular. The English plural "viruses" (which adheres to the standard rules for forming plurals) is the only way to make the noun "virus" plural.

The noun "virus" 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 virus
dress
add es viruses
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 donkey
chimney
add s donkeys
chimneys
Nouns ending f or fe dwarf
hoof
ves and/or s
(There are no rules - you have to know.)
dwarfs
hooves or hoofs
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
Foreign rulings fungus
medium
some nouns adopt foreign rulings fungi
media
Read more about English spelling rules.

Why Is There Confusion over the Plural of Virus?

"Viruses" is the only way to make the noun "virus" plural.

Confusion arises over the plural of "virus" because people mistakenly believe that "viri" or "virii" is its Latin plural form, (in the same way that fungus, cactus, and hippopotamus become fungi, cacti, and hippopotami). "Virus" is one of the few Latin nouns without a Latin plural.

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This page was written by Craig Shrives.

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