The Collaborative International Dictionary of English v.0.48:

Adoptive \A*dopt"ive\, a. [L. adoptivus: cf. F. adoptif.]
   Pertaining to adoption; made or acquired by adoption; fitted
   to adopt; as, an adoptive father, an child; an adoptive
   language. -- A*dopt"ive*ly, adv.
   [1913 Webster]