The Collaborative International Dictionary of English v.0.48:

Guilt \Guilt\ (g[i^]lt), n. [OE. gilt, gult, AS. gylt, crime;
   probably originally signifying, the fine or mulct paid for an
   offence, and afterward the offense itself, and akin to AS.
   gieldan to pay, E. yield. See Yield, v. t.]
   1. The criminality and consequent exposure to punishment
      resulting from willful disobedience of law, or from
      morally wrong action; the state of one who has broken a
      moral or political law; crime; criminality; offense
      against right.
      [1913 Webster]

            Satan had not answer, but stood struck
            With guilt of his own sin.            --Milton.
      [1913 Webster]

   2. Exposure to any legal penalty or forfeiture.
      [1913 Webster]

            A ship incurs guilt by the violation of a blockade.
                                                  --Kent.
      [1913 Webster]

   3. A feeling of regret or remorse for having committed some
      improper act; a recognition of one's own responsibility
      for doing something wrong. "Depression is often rooted in
      guilt which has not been dealt with in an appropriate
      way." "Guilt is a natural and appropriate consequence to a
      wrong action."
      [PJC]

WordNet (r) 3.0 (2006):

guilt
    n 1: the state of having committed an offense [syn: guilt,
         guiltiness] [ant: innocence]
    2: remorse caused by feeling responsible for some offense [syn:
       guilt, guilty conscience, guilt feelings, guilt trip]