The Collaborative International Dictionary of English v.0.48:

Belief \Be*lief"\, n. [OE. bileafe, bileve; cf. AS. gele['a]fa.
   See Believe.]
   1. Assent to a proposition or affirmation, or the acceptance
      of a fact, opinion, or assertion as real or true, without
      immediate personal knowledge; reliance upon word or
      testimony; partial or full assurance without positive
      knowledge or absolute certainty; persuasion; conviction;
      confidence; as, belief of a witness; the belief of our
      senses.
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            Belief admits of all degrees, from the slightest
            suspicion to the fullest assurance.   --Reid.
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   2. (Theol.) A persuasion of the truths of religion; faith.
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            No man can attain [to] belief by the bare
            contemplation of heaven and earth.    --Hooker.
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   3. The thing believed; the object of belief.
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            Superstitious prophecies are not only the belief of
            fools, but the talk sometimes of wise men. --Bacon.
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   4. A tenet, or the body of tenets, held by the advocates of
      any class of views; doctrine; creed.
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            In the heat of persecution to which Christian belief
            was subject upon its first promulgation. --Hooker.
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   Ultimate belief, a first principle incapable of proof; an
      intuitive truth; an intuition. --Sir W. Hamilton.
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   Syn: Credence; trust; reliance; assurance; opinion.
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WordNet (r) 3.0 (2006):

belief
    n 1: any cognitive content held as true [ant: disbelief,
         unbelief]
    2: a vague idea in which some confidence is placed; "his
       impression of her was favorable"; "what are your feelings
       about the crisis?"; "it strengthened my belief in his
       sincerity"; "I had a feeling that she was lying" [syn:
       impression, feeling, belief, notion, opinion]