fetus

American  

[fee-tuhs] / ˈfi təs /

especially British, foetus

noun

Embryology.

• fetuses
  plural

1. (used chiefly of viviparous mammals) the young of an animal in the womb or egg, especially in the later stages of development when the body structures are in the recognizable form of its kind, in humans after the end of the second month of gestation.

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fetus British  

/ ˈfiːtəs /

noun

1. the embryo of a mammal in the later stages of development, when it shows all the main recognizable features of the mature animal, esp a human embryo from the end of the second month of pregnancy until birth Compare embryo

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fetus Scientific  

/ fē′təs /

1. The unborn offspring of a mammal at the later stages of its development, especially a human from eight weeks after fertilization to its birth. In a fetus, all major body organs are present.

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fetus Cultural  

1. The embryo of an animal that bears its young alive (rather than laying eggs). In humans, the embryo is called a fetus after all major body structures have formed; this stage is reached about sixty days after fertilization.

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Other Word Forms

Noun Inflected Forms

• fetuses
  plural

Etymology

Origin of fetus

First recorded in 1350–1400; Middle English, from Latin fētus “bringing forth of young,” hence “that which is born, offspring, young still in the womb,” equivalent to fē- (verb base attested in Latin only in noun derivatives, as fēmina “woman,” fēcundus “fertile,” fīlius “son,” fīlia “daughter,” etc.; compare Greek thēsthai “to suck, milk,” Old High German tāan “to suck,” Old Irish denid “(he) sucks,” Slavic (Polish) doić “to milk” + -tus suffix of verb action; see fecund

Explanation

A fetus is a mammal before it's born. Once upon a time, you started as an embryo, matured into a fetus, and were then thrust into the world as a newborn. Fetus is a Latin word that means "the bearing, bringing forth, or hatching of young." Even though the Latin points to a fetus "hatching," contemporary science only regards viviparous vertebrates as having fetuses. In other words, if an animal has a backbone and was delivered via live birth, it was once a fetus. If a kitten has claws, whiskers, and ears, but is still inside its mother's womb, it's a fetus. In the UK, fetus is spelled foetus.

Example Sentences

See Examples For:

fetus fetuses

Bush, who was arrested at Heathrow Airport after returning from a holiday in the US, was not charged with denying Ness's baby a burial because of the age of the fetus.

From BBC ● Jul. 28, 2026

Researchers use it as an indirect indicator of the balance of estrogen and testosterone a fetus may have been exposed to during the first trimester of pregnancy.

From Science Daily ● Jul. 17, 2026

It is considered the safest option for treating pain and fever in pregnant women, as other medications, including aspirin or ibuprofen, present proven risks to the fetus -- as do untreated fevers.

From Barron's ● Jul. 13, 2026

She would need to cut the umbilical cord herself and return to the hospital for care in a diaper, her fetus wrapped in towels and the cord hanging between her legs.

From Salon ● May 27, 2026

French reappeared shortly before the baby was born, but the months of worrying had weakened the developing fetus; Ann lost the child soon after the birth.

From "The Best of Enemies" by Osha Gray Davidson

He specializes in treating high-risk pregnancies, from cases of eclampsia, hypertension, or gestational diabetes to patients with multiple fetuses.

From Slate ● Jun. 16, 2026

Concentrations in drinking water systems higher than 0.8 milligrams per liter can be harmful, especially to infants, young children and fetuses, according to the Environmental Protection Agency.

From Salon ● Dec. 15, 2025

Pregnant women typically take folate supplements to prevent neural tube defects in developing fetuses.

From The Wall Street Journal ● Sep. 24, 2025

You may recall a bizarre footnote to this case: protest instigator Lauren Handy, 31, was found to have five fetuses in her refrigerator.

From Los Angeles Times ● Jan. 29, 2025

In 1997 an archaeologist and a medical doctor with archaeological leanings identified them as human fetuses.

From "1491" by Charles C. Mann