1.noun(chiefly in the plural) An incompatible substance; one of a group of things that cannot be placed or used together because of a change of chemical composition or opposing medicinal qualities.
"the incompatibles of iron"
2.nounA consequent of a contrary.
3.adjectiveOf two things: that cannot coexist; not congruous because of differences
4.adjectiveIncapable of being together without mutual reaction or decomposition, as certain medicines.