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late 14c., "born prematurely or dead," from Latin abortivus "pertaining to miscarriage; causing abortion," from abort-, past participle stem of aboriri "disappear, miscarry," from ab- "amiss" (see ab-) + oriri "appear, be born, arise" (see orchestra); the compound word used in Latin for deaths, miscarriages, sunsets, etc. The Latin verb for "to produce an abortion" was abigo, literally "to drive away." Not originally used to imply forced or deliberate miscarriage; from 14c.-18c. stillborn children or domestic animals were said to be abortive. Also see abortion. Related: Abortiveness.
abortive a·bor·tive (ə-bôr'tĭv)
Not reaching completion, as of a disease subsiding before it has finished its course.
Partially or imperfectly developed; rudimentary.