(1) Not of suitable composition to be combined or mixed with another agent or substance, without resulting in an undesirable reaction (including chemical alteration or destruction or pharmacologic effect). (2) Denoting those who are unable to associate with one another without resulting anxiety and conflict. (3) Having genotypes that put progeny at high risk of severe recessive disorders or that promote harmful maternal-fetal reaction (e.g., erythroblastosis fetalis is Rh incompatible). (4) Having antigenic nonidentity between a donor and a recipient. [L. in- neg., + con-, with, + patior, pp. passus, to suffer, tolerate]