buttock

The buttock—often called the "rear" or "backside"—refers to one of the two fleshy sides of the human posterior. It’s part of normal anatomy, though many people use softer wording when talking about it directly. In contrast, "buttock" is the preferred form in clinical, fitness, and descriptive contexts. You are likely to meet it in medical notes, injury reports, or exercise instructions (for example, strengthening the muscles of the buttock).

People sometimes use the blunt word "ass" in casual speech and "butt" in slang, but those are less formal. "Buttock" is also distinct from idioms like "the butt of a joke." You will most often see it in professional descriptions rather than in casual wordplay.

The word "buttock" refers to one of the two rounded portions of the rear of the human body, forming the fleshy prominence above the hips and helping cover the sit bones (the ischial tuberosities). Anatomically, this region includes the gluteal muscles—especially the gluteus maximus, medius, and minimus. These muscles drive hip extension and help with walking, running, climbing, and cushioning the body when seated.

In professional and medical environments, "buttock" is the preferred term. Doctors, physical therapists, and trainers use it to describe anatomy clearly and respectfully. A medical report might note, "The patient received an intramuscular injection in the left buttock," while a coach may discuss strengthening the gluteal muscles to improve athletic performance.

It is important to distinguish "buttock" from its slang counterparts. Casual terms such as "butt" or "ass" are common in everyday speech, while "buttock" stays closer to neutral anatomical language. That makes it useful in exams, medical conversation, sports training, and writing about clothing fit.

Beyond biology, the word appears in arts and physical disciplines. In ballet or yoga, an instructor might say "engage the gluteal muscles" to stabilize the pelvis, and painters or sculptors may focus on the "curves of the buttocks" when depicting the human form. Idiomatic uses are uncommon, but the term remains central when discussing movement, posture, and body mechanics.