factor [noun] [C usually singular], abbreviation Rh factor [noun] [C usually singular] [specialized] - a substance in the red blood cells of most people which causes the production of antibodies in the bloodPeople whose blood contains the rhesus factor are Rh+ and those whose blood does not contain it are Rh-.See also positive (BLOOD TYPE); negative (BLOOD TYPE).
RHESUS
Meaning of RHESUS in English
Cambridge English vocab. Кембриджский английский словарь. 2012