Unnatural

wiktionary

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From Middle English unnatural, unnaturel, equivalent to un- +‎ natural.

etymonline

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unnatural (adj.)

early 15c., "not in accord with physical nature," from un- (1) "not" + natural (adj.). Meaning "artificial" is attested from 1746; that of "at variance with moral standards" is from 1520s. Related: Unnaturally; unnaturalness.