The pectoral muscle, also known as the chest muscle, is a large, fan-shaped muscle located in the chest area. There are several synonyms for this muscle, including the chest muscle, the pectoralis major, and the mammary muscle. Other synonyms for this muscle include the breast muscle and the thoracic muscle. Additionally, some people refer to this muscle as the pecs or the chest muscles. Regardless of the synonym used, the pectoral muscle is an important muscle group that plays a key role in many upper body movements, including pushing, pulling, and lifting.