The Plural of HippopotamusThe plural of hippopotamus is hippopotamuses or hippopotami.
- Hippopotamuses live in groups of up to thirty.
- Though they are bulky animals, hippopotami can gallop at 19 mph on land.
Of note, the shortened version hippos is often used in informal writing to avoid to making a decision on hippopotamuses and hippopotami.
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
|add s|| lamps
|Noun Ending s, sh, ch, x or z|| hippopotamus
|add es|| hippopotamuses
|Nouns ending [consonant] o|| hero
|add either s or es
(There are no rules for this - you have to know.)
|Nouns ending [vowel] o|| patio
|add s|| patios
|Nouns ending [consonant] y|| story
|change the y to an i and add es|| stories
|Nouns ending [vowel] y|| donkey
|add s|| donkey
|Nouns ending f or fe|| dwarf
|ves and/or s
(There are no rules - you have to know.)
hooves or hoofs
|some nouns undergo a vowel or letters change|| men
|More exceptions|| salmon
|some nouns do not change at all|| salmon
|Foreign rulings|| hippopotamus
|some nouns adopt foreign rulings|| hippopotami
Why Is There Confusion over the Plural of Hippopotamus?Confusion arises over the plural of hippopotamus because its original plural form (hippopotami) derives from Latin and native English speakers are drawn to hippopotamuses, which adheres to the standard ruling for forming plurals.
Hippopotamuses is the more common plural of the two. (See the difference in Google's Ngram Viewer.)