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.
      [1913 Webster]

   3. Charge; complaint; accusation. [Obs.] "A false
      suggestion." --Chaucer.
      [1913 Webster]

   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.
      [1913 Webster]

   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.
          [1913 Webster]

                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]

Moby Thesaurus II by Grady Ward, 1.0:

222 Moby Thesaurus words for "suggestion":
   admonition, advice, advising, advocacy, allegory, allusion,
   arcane meaning, ascendancy, aspersion, assumption, authority,
   bare suggestion, breath, briefing, broad hint, cast, catchword,
   caution, caveat, characterization, charisma, charm, clout, clue,
   coloration, connotation, consequence, consultation, control,
   council, counsel, credit, cue, cue word, dash, denomination,
   denotation, designation, differentiation, direction, disclosure,
   dominance, domination, effect, eminence, enchantment, esteem,
   evidence, exhortation, expostulation, expression, favor, fingering,
   force, gentle hint, gesture, gleam, glimmer, glimmering,
   good feeling, guidance, half an idea, hazy idea, hint, hold,
   hortation, hot lead, idea, identification, implication,
   implied meaning, import, importance, impression,
   improper suggestion, imputation, incidental power,
   indecent proposal, index, indication, indicativeness, inference,
   influence, influentiality, infusion, inkling, innuendo,
   insinuation, instance, instruction, intimation, invitation, iota,
   ironic suggestion, key, key word, kick, lead, leadership, leverage,
   lick, look, magnetism, manifestation, mastery, meaning,
   mere notion, metaphorical sense, moment, monition, motion, naming,
   nod, notion, nuance, nudge, occult meaning, opinion, overtone,
   parley, pass, personal remark, personality, persuasion,
   picking out, plan, pointing, pointing out, pointing to, potency,
   power, predominance, preponderance, pressure, prestige,
   presumption, presupposition, proffer, prompt, prompting, proposal,
   proposition, purchase, recommendation, reflection, reign, reminder,
   remonstrance, repute, request, resolution, rule, sauce, say, scent,
   scintilla, seasoning, selection, sexual advance, shade, shadow,
   show, showing, sign, signal, signification, sip, slur,
   sly suggestion, smack, smattering, smell, sneaking suspicion,
   soupcon, spark, specification, spice, spoor, sprinkling, strain,
   suasion, subsense, subsidiary sense, subtle influence, sup,
   supposition, supremacy, suspicion, sway, symbolism, symptom,
   symptomaticness, taint, taste, telltale, tempering, thought, tinct,
   tincture, tinge, tint, tip-off, touch, trace, track,
   uncomplimentary remark, undercurrent, undermeaning, undertone,
   upper hand, urging, vague idea, vein, vestige, warning, weight,
   whiff, whip hand, whisper, whispering campaign, wind, wink



Bouvier's Law Dictionary, Revised 6th Ed (1856):

SUGGESTION. In its literal sense this word signifies to inform, to
insinuate, to instruct, to cause to be remembered, to counsel. In practice
it is used to convey the idea of information; as, the defendant suggests the
death of one of the plaintiffs. 2 Sell. Pr. 191.
     2. In wills, when suggestions are made to a testator for the purpose of
procuring a devise of his property in a particular way, and when such
suggestions are false, they generally amount to a fraud. Bac. Ab. Wills, G
3; 5 Toull. n. 706.