1. A flat, quadrangular muscle, situated at the anterior (front) part of the upper and medial (inner) aspect of the thigh. The pectineus muscle is the most anterior adductor of the hip. The muscle does adduct and medially rotate the thigh but its primary function is hip flexion. (wikipedia.org)
2. A flat quadrangular muscle of the upper front and inner aspect of the thigh that arises mostly from the iliopectineal line of the pubis and is inserted along the pectineal line of the femur. (merriam-webster.com)
Word origin: From the Latin word pecten, meaning comb.