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 fetus.".
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. To miscarry, to disappear: "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 baby 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."