Adverse

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late Middle English: from Old French advers, from Latin adversus ‘against, opposite’, past participle of advertere, from ad- ‘to’ + vertere ‘to turn’. Compare with averse.

wiktionary

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First attested around 1374, from Old French avers (French adverse), from Latin adversus(“turned against”), past participle of advertere, from ad-(“to”) + vertere(“to turn”). See also versus.

etymonline

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adverse (adj.)

late 14c., "contrary, opposing," from Old French advers, earlier avers (13c., Modern French adverse) "antagonistic, unfriendly, contrary, foreign" (as in gent avers "infidel race"), from Latin adversus "turned against, turned toward, fronting, facing," figuratively "hostile, adverse, unfavorable," past participle of advertere "to turn toward," from ad "to" (see ad-) + vertere "to turn, turn back; be turned; convert, transform, translate; be changed" (from PIE root *wer- (2) "to turn, bend"). For distinction of use, see averse. Related: Adversely.