What does adversative mean?
The definition of adversative
Ad*ver”sa*tive, a.
Etym: [L. adversativus, fr. adversari.]

Expressing contrariety, opposition, or antithesis; as, an adversative conjunction (but, however, yet, etc. ); an adversative force.

— Ad*ver”sa*tive*ly, adv.

Ad*ver”sa*tive, n.
An adversative word. Harris.