Why is Adductor magnus muscle considered as a hamstring sometimes?

Adductors magnus is not considered as a hamstring muscle. Hamstrings are a group of three muscles at the back of the thigh. They are named semitendinosus, biceps femoris, and semimembranosus. The adductors are a group of five muscles on the inner side of the thigh. They are named pectineus, adductor brevis, adductor longus, adductor magnus, and gracilis.