The Collaborative International Dictionary of English v.0.48:

Practicable \Prac"ti*ca*ble\, a. [LL. practicare to act,
   transact, fr. L. practicus active, Gr. ?: cf. F. practicable,
   pratiquer to practice. See Practical.]
   1. That may be practiced or performed; capable of being done
      or accomplished with available means or resources;
      feasible; as, a practicable method; a practicable aim; a
      practicable good.
      [1913 Webster]

   2. Capable of being used; passable; as, a practicable weapon;
      a practicable road.
      [1913 Webster]

   Practicable breach (Mil.), a breach which admits of
      approach and entrance by an assailing party.
      [1913 Webster]

   Syn: Possible; feasible. -- Practicable, Possible. A
        thing may be possible, i. e., not forbidden by any law
        of nature, and yet may not now be practicable for want
        of the means requisite to its performance.
        [1913 Webster] -- Prac"ti*ca*ble*ness, n. --
        Prac"ti*ca*bly, adv.
        [1913 Webster]

WordNet (r) 3.0 (2006):

practicable
    adj 1: usable for a specific purpose; "an operable plan"; "a
           practicable solution" [syn: operable, practicable]
    2: capable of being done with means at hand and circumstances as
       they are [syn: feasible, executable, practicable,
       viable, workable]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "practicable":
   accessible, accomplishable, achievable, actable, attainable,
   banausic, compassable, doable, effective, effectual, efficient,
   employable, feasible, functional, handy, manageable, maneuverable,
   manipulatable, negotiable, operable, operatable, operative,
   overcomable, performable, possible, practical, pragmatic,
   realizable, serviceable, superable, surmountable, usable, useful,
   viable, workable