1. An involuntary ending of a pregnancy through the discharge of a fetus or the unborn vertebrate from the womb at too early a stage in its development for it to survive: Cows with Bang's disease, an infectious disease of domestic animals, often abort their calves.
2. To cause the end or termination of something: The astronauts aborted the space flight when the engine of their space ship caught fire.
3. Etymology: from abortus, a form of the Latin verb abortare, "to disappear"; formed from ab, "away" + oriori, "to come into being, to appear".