The Collaborative International Dictionary of English v.0.48:

Connotation \Con`no*ta"tion\ (k[o^]n`n[-o]*t[=a]"sh[u^]n), n.
   [Cf. F. connotation.]
   The act of connoting; a making known or designating something
   additional; implication of something more than is asserted.
   [1913 Webster]

   2. a meaning implied but not explicitly denoted by some word
      or expression, which may be understood in addition to the
      explicit primary meaning.
      [PJC]

   3. (Logic) the full set of necessary properties possessed by
      all the objects within the extension of a term; the
      intensional meaning of a term, which determines the
      objects to which the term applies; the intension of a
      term.

   Syn: intension. [PJC]

WordNet (r) 3.0 (2006):

connotation
    n 1: what you must know in order to determine the reference of
         an expression [syn: intension, connotation]
    2: an idea that is implied or suggested

Moby Thesaurus II by Grady Ward, 1.0:

78 Moby Thesaurus words for "connotation":
   affective meaning, allegory, allusion, arcane meaning, assumption,
   bearing, coloration, coloring, consequence, denotation, drift,
   effect, essence, extension, force, gist, grammatical meaning, hint,
   idea, impact, implication, implied meaning, import, inference,
   innuendo, intension, intimation, ironic suggestion,
   lexical meaning, literal meaning, meaning, metaphorical sense,
   nuance, occult meaning, overtone, pertinence, pith, point,
   practical consequence, presumption, presupposition, purport,
   range of meaning, real meaning, reference, referent, relation,
   relevance, scope, semantic cluster, semantic field, sense,
   significance, signification, significatum, signifie,
   span of meaning, spirit, structural meaning, subsense,
   subsidiary sense, substance, suggestion, sum, sum and substance,
   supposition, symbolic meaning, symbolism, tenor, tinge,
   totality of associations, touch, transferred meaning,
   unadorned meaning, undercurrent, undermeaning, undertone, value