The Collaborative International Dictionary of English v.0.48:

Suggestion \Sug*ges"tion\, n. [F. suggestion, L. suggestio.]
   1. The act of suggesting; presentation of an idea.
      [1913 Webster]

   2. That which is suggested; an intimation; an insinuation; a
      hint; a different proposal or mention; also, formerly, a
      secret incitement; temptation.
      [1913 Webster]

            Why do I yield to that suggestion?    --Shak.
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   3. Charge; complaint; accusation. [Obs.] "A false
      suggestion." --Chaucer.
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   4. (Law) Information without oath; an entry of a material
      fact or circumstance on the record for the information of
      the court, at the death or insolvency of a party.
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   5. (Physiol. & Metaph.) The act or power of originating or
      recalling ideas or relations, distinguished as original
      and relative; -- a term much used by Scottish
      metaphysicians from Hutcherson to Thomas Brown.
      [1913 Webster]

   6. (Hypnotism) The control of the mind of an hypnotic subject
      by ideas in the mind of the hypnotizer.
      [Webster 1913 Suppl.]

   Syn: Hint; allusion; intimation; insinuation.

   Usage: Suggestion, Hint. A hint is the briefest or most
          indirect mode of calling one's attention to a subject.
          A suggestion is a putting of something before the mind
          for consideration, an indirect or guarded mode of
          presenting argument or advice. A hint is usually
          something slight or covert, and may by merely negative
          in its character. A suggestion is ordinarily intended
          to furnish us with some practical assistance or
          direction. "He gave me a hint of my danger, and added
          some suggestions as to the means of avoiding it."
          [1913 Webster]

                Willing to wound, and yet afraid to strike,
                Just hint a fault, and hesitate dislike. --Pope.
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                Arthur, whom they say is killed to-night
                On your suggestion.               --Shak.
          [1913 Webster]

WordNet (r) 3.0 (2006):

suggestion
    n 1: an idea that is suggested; "the picnic was her suggestion"
    2: a proposal offered for acceptance or rejection; "it was a
       suggestion we couldn't refuse" [syn: suggestion,
       proposition, proffer]
    3: a just detectable amount; "he speaks French with a trace of
       an accent" [syn: trace, hint, suggestion]
    4: persuasion formulated as a suggestion [syn: suggestion,
       prompting]
    5: the sequential mental process in which one thought leads to
       another by association
    6: the act of inducing hypnosis [syn: hypnotism, mesmerism,
       suggestion]