The Collaborative International Dictionary of English v.0.48:

Equitable \Eq"ui*ta*ble\, a. [F. ['e]quitable, from
   ['e]quit['e]. See Equity.]
   1. Possessing or exhibiting equity; according to natural
      right or natural justice; marked by a due consideration
      for what is fair, unbiased, or impartial; just; as, an
      equitable decision; an equitable distribution of an
      estate; equitable men.
      [1913 Webster]

            No two . . . had exactly the same notion of what was
            equitable.                            --Macaulay.
      [1913 Webster]

   2. (Law) That can be sustained or made available or effective
      in a court of equity, or upon principles of equity
      jurisprudence; as, an equitable estate; equitable assets,
      assignment, mortgage, etc. --Abbott.

   Syn: Just; fair; reasonable; right; honest; impartial;
        candid; upright.
        [1913 Webster]

WordNet (r) 3.0 (2006):

equitable
    adj 1: fair to all parties as dictated by reason and conscience;
           "equitable treatment of all citizens"; "an equitable
           distribution of gifts among the children" [syn:
           equitable, just] [ant: inequitable, unjust]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "equitable":
   balanced, defensible, deserved, detached, disinterested,
   dispassionate, due, equal, equivalent, ethical, even, evenhanded,
   fair, fair and square, fair-minded, fit, good, identical,
   impartial, impersonal, indifferent, judicious, just, justifiable,
   justified, lawful, legal, level, meet, meet and right, merited,
   moral, neutral, objective, open-minded, principled, proper,
   reasonable, right, right and proper, right-minded, rightful, same,
   square, stable, tolerant, unbiased, unbigoted, uncolored,
   undazzled, uninfluenced, unjaundiced, unprejudiced, unprepossessed,
   unswayed, warrantable, warranted



Bouvier's Law Dictionary, Revised 6th Ed (1856):

EQUITABLE. That which is in conformity to the natural law. Wolff, Inst. Sec.
83.