# fetus

/ˈfitəs/ (US) · /fˈiːtəs/ (UK)

Source: https://englishreference.com/word/fetus
Updated: 2026-06-20

## Senses

### 2. unborn animal

noun · CEFR C1 · Technical

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

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

- The vet used an ultrasound to check if the horse's fetus was healthy.
- The researchers monitored the development of the whale fetus to understand how marine mammals adapt to deep-sea pressure before birth.

## 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.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.