Not capable of existing in agreement or harmony with something else: incompatible views on religion. Not capable of living or working together happily or harmoniously; antagonistic: incompatible roommates.
Impossible to be held simultaneously by one person: the incompatible offices of prosecutor and judge.
Logic That cannot be simultaneously true; mutually exclusive.
Medicine Producing an undesirable effect when used in combination with a particular substance: a medication that is incompatible with alcohol. Not immunologically compatible: incompatible blood types.