The Collaborative International Dictionary of English v.0.48:

Payable \Pay"a*ble\, a. [Cf. F. payable. Cf. Pacable.]
   1. That may, can, or should be paid; suitable to be paid;
      justly due. --Drayton.
      [1913 Webster]

            Thanks are a tribute payable by the poorest.
                                                  --South.
      [1913 Webster]

   2. (Law)
      (a) That may be discharged or settled by delivery of
          value.
      (b) Matured; now due.
          [1913 Webster]

WordNet (r) 3.0 (2006):

payable
    adj 1: subject to or requiring payment especially as specified;
           "a collectible bill"; "a note payable on demand"; "a
           check payable to John Doe" [syn: collectible,
           collectable, payable]
    n 1: a liability account showing how much is owed for goods and
         services purchased on credit; "the problem was to match
         receivables and payables in the same currency" [syn:
         account payable, payable]