English Reference

Word

fetus

Phoneticsfe·tus

US/ˈfitəs/

UK/fˈiːtəs/

UK spelling · foetus

Definition

n. an unborn or unhatched animal that has started to look like its adult form.

n. an unborn or unhatched vertebrate that has developed beyond the embryo stage and shows the basic structural features of its species.

Examples

“The doctor checked the health of the fetus during the ultrasound.”

“By the second trimester, the fetus has developed recognizable features and begins to move its limbs.”

“Medical ethics regarding the fetus often center on the point at which it can survive independently outside the womb, a threshold known as viability.”

Examples

simple

“The doctor checked the health of the fetus during the ultrasound.”

contextual

“By the second trimester, the fetus has developed recognizable features and begins to move its limbs.”

complex

“Medical ethics regarding the fetus often center on the point at which it can survive independently outside the womb, a threshold known as viability.”

Real-World Examples

“These are thought to be driven by hormones in the womb, with male foetuses exposed to more than twice the level of testosterone as females in the first and second trimesters.”
The Guardian · 21 Sept 2026
“Pregnant women, for example, were warned that ‘anger, deep sadness, fear, and similar emotions’ could kill a foetus, as could a sudden shock, such as a clap of thunder.”
Aeon · 10 Sept 2026

Etymology

A learned borrowing from Latin fētus (“offspring”). Doublet of fawn.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Synonyms

Word family

fetalAdjectivefetusNoun

Related words

This entry

Level
C1 · Advanced
Frequency
Frequent
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Technical

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English Reference