a blood group antigen possessed by Rh-positive people; if an Rh-negative person receives a blood transfusion from an Rh-positive person it can result in hemolysis and anemia
The rhesus factor is something that is in the blood of most people. If someone's blood contains this factor, they are rhesus positive. If it does not, they are rhesus negative. = Rh factor. a substance that some people have in their blood