1. Expulsion of a fetus from the womb before it is viable, however medical personnel will also use this term for a miscarriage, which is involuntary: Vivian had to go to the hospital because of an unexpected spontaneous abortion of her unborn baby.
2. Induced termination of pregnancy before the fetus is capable of independent survival: The doctor had to induce an abortion because the health and safety of the mother was at risk.
3. Anything that fails to develop, progress, or mature, such as a design, project, or a badly developed plan, etc.: The abortion of the plans to build the new civic center was regretted by just about everyone in the community.

The attempt to redesign the airplane was an abortion or failure.

4. An early or untimely abandonment of an endeavor : The inclement weather helped Norman to determine that the abortion of their hiking plans was the only safe thing to do.
5. Etymology: ab-, "from, away from" + oriri, "to come into being, to rise, to be born".

The right of a woman to have a medical operation at any time during pregnancy in which a developing fetus is removed so it is not born alive: The rallying cry of the pro-choice group at the parade was for the right of women to have abortions-on-demand.

Pertaining to opposition of the discontinuance of a pregnancy or to a fetal development: The antiabortion doctor refused to remove the fetus before it was able to survive, especially since he was not convinced that it was necessary for the mother's well- being.

A deliberate procedure to remove, or to expel, an embryo or a fetus before it is viable (able to survive) outside the uterus: The doctors recommended that Jane should have an induced abortion because giving birth to a child would very likely result in her death if she didn't have the procedure done.

A condition that exists after any of various surgical methods for terminating a pregnancy; especially during the first six months: Susan was in a clinic where she was receiving special medical treatment for the post-abortion that had been performed in order to save her life.