You searched for: “adversative
adversative (s) (noun), adversatives (pl)
A word, phrase, or clause that expresses opposition or a contrast: Examples of adversatives include such conjunctions as, "but" or "although".

Mark was talking to a friend about a trip and the possible weather conditions and he expressed an adversative when he said, "We should set a date for our journey, but if the weather is too bad, we need to plan an alternative time."

adversative (adjective), more adversative, most adversative
Pertaining to an expression of opposition or contrast by someone: Jill had an adversative reaction to what her father said about her boyfriend.