The shortened form of the word pectoralis major. Guys who take good care of there body and keep a physically active life style tend to get these. They are located in the area where women have there tits. Namely the chest. Girls like a good looking guy with nice pecs. They are usaually very muscular. They look nice too. Wish i had nice pecs.
My best friend Nick, took off his shirt and showed off his pecs. The girls love him.