Foetus - fetus

This was originally a Latin word, fetus, meaning 'offspring'. In modern English, it only means the unborn child.

There is dispute over how it should be spelled, summarised in this dictionary entry: "foetus, the usual but etymologically unsatisfactory form of fetus" (Chambers's Twentieth Century Dictionary). OED, on the other hand, says "The etymologically preferable spelling with e in this word and its cognates is adopted as the standard form in some recent Dicts., but in actual use is almost unknown."

Peter Wilson wrote in 2008: "These two definitions raise interesting thoughts about what we mean by "correct English". I was taught, as a boy, that the first spelling is the British, and the second American. It may be because of this early prejudice that I prefer what Chambers calls "the usual" spelling. I think that in most British academic writing, one should use this one; but I understand that medical subjects are moving to a preference for fetus."

Pedants of another sort will insist that it is better to use the "more etymologically satisfactory" form of fetus. If you are aware of your teacher's tastes in this matter, follow them.

See also fetid - fetor.