1) Hemagglutination 
<haematology> Agglutination of red blood cells, often used to test for the presence of antibodies directed against red cell surface antigens or carbohydrate binding proteins or viruses in a solution. Requires that the agglutinin has at least two binding sites. ... (18 Nov 1997) ... 
Agglutination of red blood corpuscles.Agglutination of red blood cells, often used to test for the presence of antibodies directed against red-cell surface antigens or carbohydrate-binding proteins or viruses in a solution. Requires that the agglutinin has at least two binding sites.