What does Masah (to rub the head with water) Mean?
Lexically, masah means to move the hand over something. It also means to wipe.
As a religious term, it means to touch an organ or something on it with something clean and wet. The object to be touched can be the head, khuf (thin-soled boots) or the bandage on a wound. It is necessary for the wetness not to be used at another place before. For instance, the wetness in the hands after washing the arms cannot be used for the masah of the head because that wetness has been used for the arms before. The hand must be wetted again and then rubbed on the head.