Grammar Monster
Grammar Monster

Plural of Amoeba

The Quick Answer
The plural of amoeba is amoebae or amoebas.

The Plural of Amoeba

The plural of amoeba is amoebae or amoebas.
  • Some amoebae are predatory and live by consuming bacteria.
  • Amoebas are so tiny that you need a microscope to see them.
The noun amoeba has a Latin root, which is the derivation of the plural amoebae. Through common usage, amoebas (which adheres to the standard rules for forming plurals) is also now acceptable.

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 amoeba
scythe
add s amoebas
scythes
Noun Ending s, sh, ch, x or z box
dress
add es boxes
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 amoeba
medium
some nouns adopt foreign rulings amoebae
media

Why Is There Confusion over the Plural of Amoeba?

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

Both amoebae and amoebas are acceptable, but amoebae is the more common plural and the safest option. (See the evidence in Google's Ngram Viewer.)