Anything abdominal relates to the midsection of your body, just below your chest and above your pelvis. Abdominal muscles are sometimes called “abs” and they’re the muscles in your abdomen.
All abdominal things relate to the belly area. If your stomach hurts, you have abdominal pain. Sit-ups are abdominal exercises. Do enough sit-ups and you'll have washboard abs because the rippled muscles look like, well, a washboard. Any stomach surgery is a type of abdominal surgery. Sometimes abdominal is used as a noun that’s short for abdominal muscle.