The Collaborative International Dictionary of English v.0.48:

Incumbrance \In*cum"brance\, n. [See Encumbrance.] [Written
   also encumbrance.]
   [1913 Webster]
   1. A burdensome and troublesome load; anything that impedes
      motion or action, or renders it difficult or laborious;
      clog; impediment; hindrance; check. --Cowper.
      [1913 Webster]

   2. (Law) A burden or charge upon property; a claim or lien
      upon an estate, which may diminish its value.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Encumbrance \En*cum"brance\, n. [Cf. OF. encombrance. Cf.
   Incumbrance.]
   1. That which encumbers; a burden which impedes action, or
      renders it difficult and laborious; a clog; an impediment.
      See Incumbrance.
      [1913 Webster]

   2. (Law) Same as Incumbrance.

   Syn: Burden; clog; impediment; check; hindrance.
        [1913 Webster]

WordNet (r) 3.0 (2006):

encumbrance
    n 1: an onerous or difficult concern; "the burden of
         responsibility"; "that's a load off my mind" [syn:
         burden, load, encumbrance, incumbrance, onus]
    2: a charge against property (as a lien or mortgage) [syn:
       encumbrance, incumbrance]
    3: any obstruction that impedes or is burdensome [syn:
       hindrance, hinderance, hitch, preventive,
       preventative, encumbrance, incumbrance, interference]

Moby Thesaurus II by Grady Ward, 1.0:

81 Moby Thesaurus words for "encumbrance":
   affliction, albatross, bale, bitter cup, bitter draft,
   bitter draught, bitter pill, burden, burden of care, burdening,
   burthen, cankerworm of care, care, cargo, charge, charging, client,
   clog, cross, crown of thorns, cumber, cumbrance, curse, deadweight,
   dependent, difficulty, disadvantage, distress, drag, embarrassment,
   freight, gall, gall and wormwood, grievance, hamper, handicap,
   hardship, hindrance, impedance, impediment, impedimenta,
   imposition, inconvenience, incubus, incumbency, infliction, lading,
   liability, load, loading, lumber, millstone, obstacle, obstruction,
   onus, oppression, overload, overtaxing, overweighting, pack,
   pack of troubles, peck of troubles, penalty, pensionary, pensioner,
   pressure, protege, public charge, saddling, sea of troubles,
   sorrow, superincumbency, surcharge, taxing, thorn, trouble, ward,
   waters of bitterness, weight, white elephant, woe



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

ENCUMBRANCE. A burden or charge upon an estate or property, so that it
cannot be disposed of without being subject to it. A mortgage, a lien for
taxes, are examples of encumbrances.
     2. These do not affect the possession of the grantee, and may be
removed or extinguished by a definite pecuniary value. See 2 Greenl. R. 22;
5 Greenl. R. 94.
     3. There are encumbrances of another kind which cannot be so removed,
such as easements for example, a highway, or a preexisting right to take
water from, the land. Strictly speaking, however, these are not
encumbrances, but appurtenances to estates in other lands, or in the
language of the civil law, servitudes. (q.v.) 5 Conn. R. 497; 10 Conn. R.
422 15 John. R. 483; and see 8 Pick. R. 349; 2 Wheat. R. 45. See 15 Verm. R.
683; l Metc. 480; 9 Metc. 462; 1 App. R. 313; 4 Ala. 21; 4 Humph. 99; 18
Pick. 403; 1 Ala. 645; 22 Pick. 447; 11 Gill & John. 472.