The Collaborative International Dictionary of English v.0.48:

Amicable \Am"i*ca*ble\, a. [L. amicabilis, fr. amicus friend,
   fr. amare to love. See Amiable.]
   Friendly; proceeding from, or exhibiting, friendliness; after
   the manner of friends; peaceable; as, an amicable
   disposition, or arrangement.
   [1913 Webster]

         That which was most remarkable in this contest was . .
         . the amicable manner in which it was managed.
                                                  --Prideoux.
   [1913 Webster]

   Amicable action (Law.), an action commenced and prosecuted
      by amicable consent of the parties, for the purpose of
      obtaining a decision of the court on some matter of law
      involved in it. --Bouvier. --Burrill.

   Amicable numbers (Math.), two numbers, each of which is
      equal to the sum of all the aliquot parts of the other.
      [1913 Webster]

   Syn: Friendly; peaceable; kind; harmonious.

   Usage: Amicable, Friendly. Neither of these words denotes
          any great warmth of affection, since friendly has by
          no means the same strength as its noun friendship. It
          does, however, imply something of real cordiality;
          while amicable supposes very little more than that the
          parties referred to are not disposed to quarrel.
          Hence, we speak of amicable relations between two
          countries, an amicable adjustment of difficulties.
          "Those who entertain friendly feelings toward each
          other can live amicably together."
          [1913 Webster]

WordNet (r) 3.0 (2006):

amicable
    adj 1: characterized by friendship and good will [ant:
           hostile]

Moby Thesaurus II by Grady Ward, 1.0:

94 Moby Thesaurus words for "amicable":
   accordant, affable, agreeable, agreeing, akin, amiable, at one,
   attuned, beneficent, benevolent, benign, benignant, blissful,
   brotherly, cheerful, civil, compatible, complaisant, concordant,
   congenial, cooperative, cordial, corresponding, courteous,
   desirable, dulcet, empathetic, empathic, en rapport, enjoyable,
   fair, fair and pleasant, favorable, felicific, felicitous, fine,
   fraternal, frictionless, friendlike, friendly, genial, good,
   goodly, gracious, grateful, gratifying, harmonious, heart-warming,
   honeyed, in accord, in concert, in rapport, in tune, inharmony,
   kind, kindly, kindly-disposed, likable, like-minded, mellifluous,
   mellow, neighborlike, neighborly, nice, of one mind, pacific,
   peaceable, peaceful, pleasant, pleasing, pleasurable,
   pleasure-giving, pleasureful, polite, propitious, rewarding,
   satisfying, simpatico, sisterly, sociable, sweet, sympathetic,
   sympathique, together, understanding, unhostile, united, warm,
   welcome, well-affected, well-disposed, well-intentioned,
   well-meaning, well-meant