Qué es pectoral? Qué es pectoral? Relating to or situated in the breast or chest: a pectoral muscle; the pectoral cavity. Useful in relieving disorders of the chest or respiratory tract.Worn on the chest or breast: a pectoral cross. A muscle or organ of the chest.A pectoral fin.A medicine for relieving disorders of the chest or respiratory tract.An ornament or decoration worn on the chest.