The Collaborative International Dictionary of English v.0.48:

Insinuate \In*sin"u*ate\, v. t. [imp. & p. p. Insinuated; p.
   pr. & vb. n. Insinuating.] [L. insinuatus, p. p. of
   insinuareto insinuate; pref. in- in + sinus the bosom. See
   Sinuous.]
   [1913 Webster]
   1. To introduce gently or slowly, as by a winding or narrow
      passage, or a gentle, persistent movement.
      [1913 Webster]

            The water easily insinuates itself into, and
            placidly distends, the vessels of vegetables.
                                                  --Woodward.
      [1913 Webster]

   2. To introduce artfully; to infuse gently; to instill.
      [1913 Webster]

            All the art of rhetoric, besides order and
            clearness, are for nothing else but to insinuate
            wrong ideas, move the passions, and thereby mislead
            the judgment.                         --Locke.
      [1913 Webster]

            Horace laughs to shame all follies and insinuates
            virtue, rather by familiar examples than by the
            severity of precepts.                 --Dryden.
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   3. To hint; to suggest by remote allusion; -- often used
      derogatorily; as, did you mean to insinuate anything?
      [1913 Webster]

   4. To push or work (one's self), as into favor; to introduce
      by slow, gentle, or artful means; to ingratiate; -- used
      reflexively.
      [1913 Webster]

            He insinuated himself into the very good grace of
            the Duke of Buckingham.               --Clarendon.

   Syn: To instill; hint; suggest; intimate.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Insinuating \In*sin"u*a`ting\, a.
   Winding, creeping, or flowing in, quietly or stealthily;
   suggesting; winning favor and confidence insensibly.
   --Milton.
   [1913 Webster]

         His address was courteous, and even insinuating.
                                                  --Prescott.
   [1913 Webster]

WordNet (r) 3.0 (2006):

insinuating
    adj 1: calculated to please or gain favor; "a smooth
           ingratiating manner" [syn: ingratiating, insinuating,
           ingratiatory]

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "insinuating":
   adulatory, allusive, allusory, bland, blandishing, blarneying,
   buttery, cajoling, complimentary, courtierly, courtly, deferential,
   disarming, fair-spoken, fawning, fine-spoken, flattering, fulsome,
   gushing, honey-mouthed, honey-tongued, honeyed, implicational,
   implicative, implicatory, indicative, inferential, insincere,
   insinuative, insinuatory, ironic, mealymouthed, obsequious, oily,
   oily-tongued, referential, saccharine, silken, silky, slimy,
   slobbery, smarmy, smooth, smooth-spoken, smooth-tongued, soapy,
   soft-soaping, suggestive, sycophantic, unctuous, wheedling