Any of a group of unequal or dissimilar things.
Utterly unlike; incapable of being compared; having no common ground.
Composed of inherently different or distinct elements; incongruous.
Essentially different; of different species, unlike but not opposed in pairs
Any adjective that is not gradable.
That cannot be graded.
(of an adjective) Describing a quality that cannot normally be varied because it is extreme (e.g. freezing), absolute (e.g. dead), or classification (e.g. nuclear).