pectoral muscle definition
Definition of PECTORAL MUSCLE. : any of the muscles which connect the ventral walls of the chest with the bones of the upper arm and shoulder and of which there are two on each side of the human body.See pectoral muscle defined for kids.ADVERTISEMENT. any of the muscles which connect the ventral walls of the chest with the bones of the upper arm and shoulder and of which there are two on each side of the human body. See pectoral muscle defined for kids. ADVERTISEMENT.