foetus

Usage notes
The form is the primary spelling in the United States, Canada, Australia and in the scientific community, whereas  is still commonly used in the United Kingdom and some other Commonwealth nations. Sometimes considered less correct than fetus and suggested to be abandoned.

Etymology
From.

Noun

 * 1) fetus

Etymology
Introduced after 600 by Isidorus (c. 560–636 ), who wrote “Etymologies”, much of which was erroneous, partly because his Latin was, as described, “not pure”, and appears to have been misled by the, itself a later corruption of.