The Collaborative International Dictionary of English v.0.48:

Opine \O*pine"\, v. t. & i. [imp. & p. p. Opined; p. pr. & vb.
   n. Opining.] [L. opinari, p. p. opinatus; akin to opinus
   (in comp.) thinking, and perh. to E. apt: cf. F. opiner.]
   To have an opinion; to judge; to think; to suppose. --South.
   [1913 Webster]

WordNet (r) 3.0 (2006):

opine
    v 1: express one's opinion openly and without fear or
         hesitation; "John spoke up at the meeting" [syn: opine,
         speak up, speak out, animadvert, sound off]
    2: expect, believe, or suppose; "I imagine she earned a lot of
       money with her new novel"; "I thought to find her in a bad
       state"; "he didn't think to find her in the kitchen"; "I
       guess she is angry at me for standing her up" [syn: think,
       opine, suppose, imagine, reckon, guess]