haemagglutinationEnglishOxford Dictionary of Englishhaemagglutination /ˌhiːməɡluːtɪˈneɪʃn / (US English hemagglutination) ▸ noun [mass noun] Medicine Biology the clumping together of red blood cells. – DERIVATIVES haemagglutinate /ˌhiːməˈɡluːtɪneɪt/ (US English hemagglutinate) verb