The Collaborative International Dictionary of English v.0.48:

Insolvent \In*sol"vent\, a. [Pref. in- not + solvent: cf. OF.
   insolvent.] (Law)
      (a) Not solvent; not having sufficient estate to pay one's
          debts; unable to pay one's debts as they fall due, in
          the ordinary course of trade and business; as, in
          insolvent debtor.
      (b) Not sufficient to pay all the debts of the owner; as,
          an insolvent estate.
      (c) Relating to persons unable to pay their debts.
          [1913 Webster]

   Insolvent law, or Act of insolvency, a law affording
      relief, -- subject to various modifications in different
      States, -- to insolvent debtors, upon their delivering up
      their property for the benefit of their creditors;
      bankruptcy law. See Bankrupt law, under Bankrupt, a.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Insolvent \In*sol"vent\, n. (Law)
   One who is insolvent; as insolvent debtor; -- in England,
   before 1861, especially applied to persons not traders.
   --Bouvier.
   [1913 Webster]

WordNet (r) 3.0 (2006):

insolvent
    adj 1: unable to meet or discharge financial obligations; "an
           insolvent person"; "an insolvent estate" [ant: solvent]
    n 1: someone who has insufficient assets to cover their debts
         [syn: bankrupt, insolvent]