An abortion is the removal or expulsion of an embryo or fetus from the uterus, resulting in or caused by its death.
This can occur spontaneously as a miscarriage, or be artificially induced through chemical, surgical or other means.
Commonly, "abortion" refers to an induced procedure at any point in the pregnancy; medically, it is defined as a miscarriage or induced termination before twenty weeks' gestation, which is considered nonviable.
A pregnancy that ends earlier than 37 complete weeks of gestation, and where an infant is born and survives, is termed a premature birth.
A pregnancy that ends with an infant dead upon birth at any gestational stage, due to causes including spontaneous abortion or complications during delivery, is termed a stillbirth.
In common parlance, the term "abortion" is synonymous with induced abortion of a human fetus.
However, in medical texts, the word 'abortion' can also refer to spontaneous abortion (miscarriage).