The Collaborative International Dictionary of English v.0.48:

Indebtedness \In*debt"ed*ness\, n.
   1. The state of being indebted.
      [1913 Webster]

   2. The sum owed; debts, collectively.
      [1913 Webster]

WordNet (r) 3.0 (2006):

indebtedness
    n 1: an obligation to pay money to another party [syn:
         indebtedness, liability, financial obligation]
    2: a personal relation in which one is indebted for a service or
       favor [syn: obligation, indebtedness]

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "indebtedness":
   accounts payable, accounts receivable, amount due, arrearage,
   arrears, bad debts, bankruptcy, bill, bills, borrowing, charges,
   chits, debt, delinquency, due, dues, failure, financial commitment,
   floating debt, funded debt, indebtment, insolvency, liability,
   maturity, national debt, nonpayment, obligation, outstanding debt,
   pledge, public debt, score, uncollectibles, unfulfilled pledge



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

INDEBTEDNESS. The state, of being in debt, without regard to the ability or
inability of the party to pay the same. See 1 Story, Eq. 343; 2 Hill. Ab.
421.
     2. But in order to create an indebtedness, there must be an actual
liability at the time, either to pay then or at a future time. If, for
example, a person were to enter and become surety for another, who enters
into a rule of reference, he does not thereby become a debtor to the
opposite party until the rendition of the judgment on the award. 1 Mass.
134. See Creditor; Debt; Debtor.