adversative
adjective
ad·ver·sa·tive əd-ˈvər-sə-tiv 
ad-
: expressing antithesis, opposition, or adverse circumstance
the adversative conjunction but
adversative noun
adversatively adverb
Word History
Etymology
Middle English adversatyf, borrowed from Late Latin adversātīvus, from Latin adversātus, past participle of adversārī "to act contrary to, oppose" (derivative of adversus adverse) + -īvus -ive
First Known Use
15th century, in the meaning defined above