Plural of Fetus
The Quick AnswerThe plural of fetus is fetuses or feti .
The Plural of FetusThe plural of fetus is fetuses or, less commonly, feti.
- Female fetuses tend to weigh less than males, at full term.
- The detection of multiple feti can be made by using ultrasound technology.
Are You Good at Plurals?Here's a quick test.
The Standard Rules for Forming the PluralsThe 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|| fetus
|add es|| fetuses
|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|| donkeys
|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|| fetus
|some nouns adopt foreign rulings|| feti
Why Is There Confusion over the Plural of Fetus?Confusion arises over the plural of fetus because its original plural form (feti) derives from Latin and native English speakers are drawn to fetuses, which adheres to the standard ruling for forming plurals.
Both fetuses and feti are acceptable. Of note, fetuses is by far the more common plural. (See the evidence in Google's Ngram Viewer.)