Agglutinogens are antigens found on the surface of red blood cells that can trigger the production of agglutinins in the blood. These agglutinins are antibodies that bind to and agglutinate (clump together) red blood cells, causing agglutination reactions. Synonyms for the term agglutinogens include blood-group substances, erythrocyte antigens, and isoagglutinogens. Isoagglutinogens are agglutinogens belonging to different blood groups, which can cause transfusion reactions if the wrong blood type is administered. Knowing the different synonyms for an important term like agglutinogens is crucial for healthcare professionals and students who deal with blood transfusions and blood typing on a regular basis.