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Plural of Nucleus

The Quick Answer
The plural of nucleus is nuclei.

The Plural of Nucleus

The plural of nucleus is nuclei. The alternative plural nucleuses is extremely rare but still acceptable.
  • Cell nuclei contain most of the cell's genetic material.
  • Some eukaryotic cell types have no nuclei.
  • Some cell types have many nucleuses.
The noun nucleus has a Latin root, which is the derivation of the plural nuclei. Nucleuses (which adheres to the standard rules for forming plurals) is also an accepted plural.

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 nucleus
dress
add es nucleuses
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 donkey
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 nucleus
medium
some nouns adopt foreign rulings nuclei
media

Why Is There Confusion over the Plural of Nucleus?

Confusion arises over the plural of nucleus because its original plural form (nuclei) derives from Latin and native English speakers are drawn to nucleuses, which adheres to the standard ruling for forming plurals.

Nuclei is by far the more common plural of the two. (See the difference in Google's Ngram Viewer.)