contrary to the laws or course of nature.

at variance with the character or nature of a person, animal, or plant.

at variance with what is normal or to be expected

the unnatural atmosphere of the place.

lacking human qualities or sympathies; monstrous; inhuman

an obsessive and unnatural hatred.

not genuine or spontaneous; artificial or contrived

a stiff, unnatural manner.

Obsolete . lacking a valid or natural claim; illegitimate.

adjective

acceptable , genuine , natural , real

adjective

aberrant , abnormal , affected , anomalous , assumed , bizarre , concocted , contrary , contrived , ersatz * , extraordinary , fabricated , factitious , false , feigned , forced , freakish , freaky , imitation , incredible , insincere , irregular , labored , made-up * , make-believe * , odd , outlandish , outrageous , perverse , perverted , phony , preposterous , pseudo * , put-on , queer , staged , stiff , stilted * , strained , strange , studied , supernatural , synthetic , theatrical , unaccountable , uncanny , unconforming , unorthodox , unusual , cranky , curious , erratic , idiosyncratic , peculiar , quaint , quirky , singular , weird , anomalistic , atypic , atypical , deviant , divergent , preternatural , artificial , assumed simulated , constrained , exceptional , fake , monstrous , variant