1570s, "to miscarry in giving birth," from Latin abortus, past participle of aboriri "to miscarry, be aborted, fail, disappear, pass away," a compound word used in Latin for deaths, miscarriages, sunsets, etc., which according to OED is from ab, here as "amiss" (see ab-), + stem of oriri "appear, be born, arise," from PIE *heri- "to rise" (see origin). [Watkins, contra de Vaan, etc., derives the second element from a suffixed form of PIE root *er- (1) "move, set in motion."]
From 1610s as "to deliberately terminate" anything, but especially a pregnancy. Intransitive use in aeronautics and space-flight is by 1946. Transitive meaning "to cause (a woman) to miscarry" is recorded from 1933; with the fetus or pregnancy as the object of the action by 1974. Related: Aborted; aborting. The Latin verb for "produce an abortion" was abigo, literally "to drive away."