In various specific applications. a blood-group (see quots.).

Medicine. Chiefly in form A. Denoting one of the principal erythrocyte antigens (agglutinogens) of the ABO blood group system, and the blood type…

Medicine. Originally: denoting absence of the A and B agglutinogens of the ABO blood group system. Now usually: denoting the blood group…

Used attributively with reference to a major human blood group system originally identified by means of rabbit antisera to rhesus monkey blood…

a rhesus antigen, spec. the major (D) antigen.