adverse

Etymology

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.

adj

1. Unfavorable; antagonistic in purpose or effect; hostile; actively opposing one's interests or wishes; contrary to one's welfare; acting against; working in an opposing direction.
   adverse criticism
   adverse weather
   Northbound expresses have the hardest work to perform, with adverse grades predominating from Willesden to Tring. 1960 February, R. C. Riley, “The London-Birmingham services - Past, Present and Future”, in Trains Illustrated, page 98
   Several types of diesel locomotive have been tested on this working and as a result the probable choice will be Type 2 diesels in pairs, without bankers. The crucial factor in the selection of this method is the higher degree of adhesion obtained than with a single Type 4; on trial one of the latter showed that in very adverse conditions it might slip to a standstill at one of the two tricky spots on the steep climb from Tyne Dock to Consett. 1964 September, “News: Fewer diesels for NER in 1965”, in Modern Railways, page 201
   He said Robins had not been in trouble with the law before and had no previous convictions. Jail would have an adverse effect on her and her three children as she was the main carer. December 14, 2011, Steven Morris, “Devon woman jailed for 168 days for killing kitten in microwave”, in Guardian
2. Opposed; contrary; opposing one's interests or desire.
   adverse circumstances
3. (not comparable) Opposite; confronting.
   the adverse page
   the adverse party
   Calpe's adverse height / […] must greet my sight 1809, Lord Byron, English Bards and Scotch Reviewers
   Now the families of the two lovers were not on very good terms; they were, I believe, rather adverse to one another. 1835, James Hogg, The Story of Euphemia Hewit