The Collaborative International Dictionary of English v.0.48:

Insinuation \In*sin"u*a`tion\, n. [L. insinuatio: cf. F.
   insinuation.]
   [1913 Webster]
   1. The act or process of insinuating; a creeping, winding, or
      flowing in.
      [1913 Webster]

            By a soft insinuation mix'd
            With earth's large mass.              --Crashaw.
      [1913 Webster]

   2. The act of gaining favor, affection, or influence, by
      gentle or artful means; -- formerly used in a good sense,
      as of friendly influence or interposition. --Sir H.
      Wotton.
      [1913 Webster]

            I hope through the insinuation of Lord Scarborough
            to keep them here till further orders. --Lady
                                                  Cowper.
      [1913 Webster]

   3. The art or power of gaining good will by a prepossessing
      manner.
      [1913 Webster]

            He bad a natural insinuation and address which made
            him acceptable in the best company.   --Clarendon.
      [1913 Webster]

   4. That which is insinuated; a hint; a suggestion or
      intimation by distant allusion; as, slander may be
      conveyed by insinuations.
      [1913 Webster]

            I scorn your coarse insinuation.      --Cowper.

   Syn: Hint; intimation; suggestion. See Innuendo.
        [1913 Webster]

WordNet (r) 3.0 (2006):

insinuation
    n 1: an indirect (and usually malicious) implication [syn:
         insinuation, innuendo]
    2: the act of gaining acceptance or affection for yourself by
       persuasive and subtle blandishments; "she refused to use
       insinuation in order to gain favor" [syn: ingratiation,
       insinuation]