\Ad*ver"sa*tive\, a. [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.