[Say “al-oh-jin-A-ic”] Literally, “being genetically different although belonging to or obtained from the same species.” In blood banking, allogeneic transfusion
is when a donor and a recipient are not the same person (in contrast to autologous
transfusion, where donor and recipient are the same person). The word describes the vast majority of routine transfusions, to the point where when we would properly
say, “The patient received an allogeneic red blood cell transfusion,” the “allogeneic” part is just assumed and not usually said (“The patient received a red blood cell transfusion”).
The directed transfusion, where a specific person donates blood for a specific patient, is a subtype of allogeneic transfusion; directed donations are very uncommon now due to the increased safety of the blood supply.
Note that the term “homologous transfusion” means exactly the same thing! Sometimes, evil test question-writers will try to confuse you by using “homologous” instead of allogeneic because it sounds a lot like “autologous” (donor = recipient). Don’t be fooled!