fetus

American  

[fee-tuhs] / ˈfi təs /

especially British, foetus

noun

Embryology.

plural

fetuses

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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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; fecund

Example Sentences

Although prior immunity usually protects the fetus, routine screening is not available in some countries, highlighting the challenges of managing an infection that is widespread but often symptom-free.

From Science Daily • Jan. 27, 2026

In the interim, it lurks underground in stasis, almost like a fetus in the womb.

From Salon • Nov. 9, 2025

Cells from older biological siblings—or even the mother’s relatives—can end up inside the fetus.

From The Wall Street Journal • Nov. 4, 2025

Fevers can harm the fetus and have been associated with autism and ADHD.

From The Wall Street Journal • Oct. 29, 2025

Limbs, torsos, brains, eyes, faces—even temperaments or propensities that were inherited—had to be created anew each time an embryo unfurled into a human fetus.

From "The Gene" by Siddhartha Mukherjee