The Collaborative International Dictionary of English v.0.48:

Amusive \A*mu"sive\ (?; 277), a.
   Having power to amuse or entertain the mind; fitted to excite
   mirth. [R.] -- A*mu"sive*ly, adv. -- A*mu"sive*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

amusive
    adj 1: providing enjoyment; pleasantly entertaining; "an amusing
           speaker"; "a diverting story" [syn: amusing, amusive,
           diverting]