There are several synonyms for the term "rhesus factor", which refers to a type of protein that is found on the surface of red blood cells in many individuals. One alternate term is "Rh factor", which is commonly used in medical settings. Another synonym is "D antigen", which refers specifically to the protein variant that is responsible for the rhesus factor. Other related terms include "rhesus protein", "Rh blood group system", and simply "Rh". These terms are important to understand in clinical contexts, as the presence or absence of the rhesus factor can impact the risk of certain health complications during pregnancy and blood transfusions.