Origin and history of feticide

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, pregnancy, childbearing, offspring," from suffixed form of PIE root *dhe(i)- "to suck."

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 usual 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 unetymological (see oe).

word-forming element meaning "killer," from French -cide, from Latin -cida "cutter, killer, slayer," from -cidere, combining form of caedere "to fall, fall down, fall away, decay, fall dead" (from Proto-Italic *kaid-o-, from PIE root *kae-id- "to strike"). For the Latin vowel change, compare acquisition.

The element also can represent "killing," from French -cide, from Latin -cidium "a cutting, a killing." But it has a classical literal sense in stillicide.