fetus
/ˈfiːtəs/noun
fetus is a noun meaning “An unborn or unhatched vertebrate showing signs of the mature animal” (English Wiktionary, September 2026). It is spelled F-E-T-U-S and has 2 syllables, and it appears 4.0 times per million words in written English (wordfreq, 2021 data). The plural of fetus is fetuses or fetii; Wiktionary also lists feti (hypercorrect).
What does fetus mean?
noun
- 1
AustraliaCanadaUSAn unborn or unhatched vertebrate showing signs of the mature animal.
Several feti were removed from every rats' uterus, stripped of their membranes and allowed to lie in the peritoneal cavity connected to the placenta by the umbilical cord and with the placenta still attached to the uterine wall.
- 2
AustraliaCanadaUSA human embryo after the eighth week of gestation.
The sequence is: molecules in reproductive systems, then gametes, zygotes, morulas, blastocysts, and then fetuses.
- 3
AustraliaCanadaUSarchaicA neonate.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
How do you pronounce fetus?
- /ˈfiːtəs/
Fetus has 2 syllables (counted from its American pronunciation in the CMU Pronouncing Dictionary).
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: LL-Q1860_(eng)-Vealhurl-foetus.wav, Wikimedia Commons (author and licence on each file's page).
Forms of fetus
- fetuses plural
- feti hypercorrect, plural
- fetii plural
- foetus
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
How common is fetus?
Fetus appears 4.0 times per million words in written English, the 12,940th most frequent word form in the list.
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
Words people confuse with fetus
Word pairs people search, with the monthly searches for “a vs b” (G: Google, B: Bing, United States).
Also written: foetus.
Sources: Google and Bing searches (September 2025 to August 2026, through DataForSEO); English Wiktionary (homophones, alternative spellings).
Fetus in Spanish, French, German and Portuguese
In the sense an unborn or unhatched vertebrate showing signs of the mature animal:
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.
Where does fetus come from?
A learned borrowing from Latin fētus (“offspring”). Doublet of fawn.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).