One of the several groups into which all human blood can be categorized: A, B, AB, and O.
The type and subtype of an individual’s blood; specified as A, B, AB, or O; Rh-negative or Rh-positive; and including a number of subtypes. It is important to determine the blood type when a woman is pregnant or when a patient needs a transfusion in order to avoid a dangerous reaction with an incompatible type.
In the domain of blood classification, there are distinct categories determined by the presence or absence of specific antigens on the surface of red blood cells.