home > medterms medical dictionary a-z list > abortion, spontaneous definition smallermediumlarger Definition of Abortion, spontaneous Abortion, spontaneous: Miscarriage.Last Editorial Review: 7/1/2016 Search MedTerms:Back to MedTerms online medical dictionary A-Z List Need help identifying pills and medications? Use the pill finder tool on RxList. STAY INFORMED Get the latest health and medical information delivered direct to your inbox! From Women's Health Resources Video: Emotional Resilience Featured Centers Feeling Short of Breath? What to Eat When You Have Cancer Top 3 Anaphylaxis Triggers Exclusives What Does Psoriasis Look Like? How to Prevent Muscle Cramps Blood Clot? Know the Signs and Symptoms Allergy Triggers: Do You Know Yours?