Unholy

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Old English unhālig (see un-1, holy).

wiktionary

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From Middle English unholi, unhaliȝ, from Old English unhāliġ, from Proto-Germanic *unhailagaz, equivalent to un- +‎ holy. Cognate with Scots unhaly, Dutch onheilig, German Low German unhillig, German unheilig, Danish uhellig, Swedish ohelig.

etymonline

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unholy (adj.)

Old English unhalig, "impious, profane, wicked," from un- (1) "not" + halig (see holy). Similar formation in Middle Dutch onheilich, Old Norse uheilagr, Danish unhellig, Swedish ohelig. In reference to actions, it is attested from late 14c. Colloquial sense of "awful, dreadful" is recorded from 1842.