late 14c., "the young while in the womb or egg" (tending to mean vaguely the embryo in the later stage of development), from Latin fetus (often, incorrectly, foetus) "the bearing or hatching of young, a bringing forth," from Latin base *fe- "to generate, bear," also "to suck, suckle" (see fecund).
In Latin, fetus sometimes was transferred figuratively to the newborn creature itself, or used in a sense of "offspring, brood" (as in Horace's "Germania quos horrida parturit Fetus"), but this was not the basic meaning. It also was used of plants, in the sense of "fruit, produce, shoot," and figuratively as "growth, production." The spelling foetus is sometimes attempted as a learned Latinism, but it is not historic.
例文
1. Surely the fetus has a right to life？
胎児には確かに生命権があるのだろうか。
2.Microscopic examination of a cell 's chromo-somes can reveal the sex of the fetus .
細胞染色体を顕微鏡で検査すると胎児の性別を発見することができる。
3.No one knows why a fetus is not automatically rejected by the mother 's immune system.
母親の免疫系が胎児を自動的に排斥しない理由を知っている人はいない。
4.Unfortunately，his wife had just given birth to a nonviable fetus .
残念ながら、彼の妻は生きられない胎児を産んだばかりだ。
5.A routine scan revealed abnormalities in the fetus .