Unnatural, a.
Not natural; contrary, or not conforming, to the order of nature; being without natural traits; as, unnatural crimes.
Syn. -- See Factitious. -- Un*nat"u*ral*ly, adv. -- Un*nat"u*ral*ness, n.
Shades of meaning
Fernald lists unnatural only as an antonym, under native.
He lists it without comment; the entries above explain its neighbors.
Synonyms
none given