abort /əbôrt″/ [L, ab, away from, oriri, to be born] , 1. (Nontechnical) to deliver a nonviable fetus; to miscarry. Now called miscarriage. See also spontaneous abortion. 2. to terminate a pregnancy before the fetus has developed enough to be viable. See also induced abortion. 3. to terminate in the early stages or to discontinue before completion, as to arrest the usual course of a disease, to stop growth and development, or to halt a project.