The Collaborative International Dictionary of English v.0.48:

Forfeiture \For"fei*ture\ (?; 135), n. [F. forfeiture, LL.
   forisfactura.]
   1. The act of forfeiting; the loss of some right, privilege,
      estate, honor, office, or effects, by an offense, crime,
      breach of condition, or other act.
      [1913 Webster]

            Under pain of foreiture of the said goods.
                                                  --Hakluyt.
      [1913 Webster]

   2. That which is forfeited; a penalty; a fine or mulct.
      [1913 Webster]

            What should I gain
            By the exaction of the forfeiture?    --Shak.

   Syn: Fine; mulct; amercement; penalty.
        [1913 Webster]

WordNet (r) 3.0 (2006):

forfeiture
    n 1: something that is lost or surrendered as a penalty; [syn:
         forfeit, forfeiture]
    2: a penalty for a fault or mistake that involves losing or
       giving up something; "the contract specified forfeits if the
       work was not completed on time" [syn: forfeit,
       forfeiture]
    3: the act of losing or surrendering something as a penalty for
       a mistake or fault or failure to perform etc. [syn:
       forfeit, forfeiture, sacrifice]

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "forfeiture":
   amercement, bereavement, cost, damage, damages, dead loss, debit,
   denial, denudation, deprivation, despoilment, destruction,
   detriment, dispossession, distraint, distress, divestment, escheat,
   escheatment, expense, fine, forfeit, injury, loser, losing,
   losing streak, loss, mulct, perdition, privation, robbery, ruin,
   sacrifice, sconce, spoliation, stripping, taking away,
   total loss



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

FORFEITURE, punishment, torts. Forfeiture is a punishment annexed by law to
some illegal act, or negligence, in the owner of lands, tenements, or
hereditaments, whereby he loses all his interest therein, and they become
vested in the party injured, as a recompense for the wrong which he alone,
or the Public together with himself, hath sustained. 2 Bl. Com. 267.
     2. Lands, tenements and hereditaments, may be forfeited by various
means: 1. By the commission of crimes and misdemeanors. 2. By alienation
contrary to law. 3. By the non-performance of conditions. 4. By waste.
     3. - 1. Forfeiture for crimes. By the Constitution of the United
States, art. 3, s. 3, it is declared that no attainder of treason shall work
corruption of blood, or forfeiture, except during the life of the person
attainted. And by the Act of April 30, 1790, s. 24, 1 Story's Laws U. S. 88,
it is enacted, that no conviction or judgment for any of the offences
aforesaid, shall work corruption of blood, or any forfeiture of estate. As
the offences punished by this act are of the blackest dye, including cases
of treason, the punishment of forfeiture may be considered as being
abolished. The forfeiture of the estate for crime is very much reduced in
practice in this country, and when it occurs, the stater takes the title the
party had, and no more. 4 Mason's R. 174; Dalrymple on Feudal Property, c.
4, p. 145-154; Fost. C. L. 95.
     4. - 2. Forfeiture by alienation. By the English law, estates less than
a fee may be forfeited to the party entitled to the residuary interest by a
breach of duty in the owner of the particular estate. When a tenant for life
or years, therefore, by feoffment, fine, or recovery, conveys a greater
estate than he is by law entitled to do, he forfeits his estate to the
person next entitled in remainder or reversion. 2 Bl. Com. 274. In this
country, such forfeitures are almost unknown, and the more just principle
prevails, that the conveyance by the tenant operates only on the interest
which he possessed, and does not affect the remainder-man or reversioner. 4
Kent, Com. 81, 82, 424; 1 Hill. Ab. c. 4, s. 25 to 34; 3 Dall. Rep. 486; 5
Ohio, R. 30.
     5. - 3. Forfeiture by non-performance of conditions. An estate may be
forfeited by a breach, or non-performance of a condition annexed to the
estate, either expressed in the deed at its original creation, or impliedly
by law, from a principle of natural reason. 2 Bl. Com. 281; and see Ad
Eject. 140 to 173. Vide article Reentry; 12 Serg. & Rawle, 190.
     6. - 4. Forfeiture by waste. Waste is also a cause of forfeiture. 2 Bl.
Com. 283. Vide article Waste.
     7. By forfeiture is also understood the neglect of an obligor to fulfill

his obligation in proper time: as, when one has entered into a bond for a
penal sum, upon condition to pay a smaller at a particular day, and he fails
to do it, there is then said to be a forfeiture. Again, when a party becomes
bound in a certain sum by a recognizance to pay a certain sum, with a
condition that he will appear at court to answer or prosecute a crime, and
he fails to do it, there is a forfeiture of the recognizance. Courts of
equity, and now courts, of law, will relieve from the forfeiture of a bond;
and upon a proper case shown, criminal courts will in general relieve from
the forfeiture of a recognizance to appear. See 3 Yeates, 93; 2 Wash. C. C.
442 Blackf. 104, 200; Breeze, 257. Vide, generally, 2 Bl. Com. ch. 18; Bouv.
Inst. Index, h.t.; 2 Kent's Com; 318; 4 Id. 422; 10 Vin. Ab. 371, 394 13
Vin. Ab. 436; Bac. Ab. Forfeiture Com. Dig. h.t.; Dane's Ab. h.t.; 1 Bro
Civ. L. 252 4 Bl. Com. 382; and Considerations on the Law of Forfeiture for
High Treason, London ed. l746.