Definition of Gluteus maximus

Gluteus maximus: The greatest gluteal muscle and the biggest muscle in the human body. The gluteus maximus forms the bulk of the buttocks. It acts to extend the upper leg, spread it, and turn it outward. There are two other gluteal muscles called the gluteus medius and gluteus minimus. Together with the gluteus maximus, they may sound like three Roman emperors but are the muscles we sit upon.