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
The two words adverse and averse are related in origin but they do not have the same meaning. Adverse means ‘unfavourable or harmful’ and is normally used of conditions and effects rather than people, as in adverse weather conditions. Averse, on the other hand, is used of people, nearly always with to, and means ‘having a strong dislike or opposition to something’, as in I am not averse to helping out. A common error is to use adverse instead of averse, as in he is not adverse to making a profit.