The Collaborative International Dictionary of English v.0.48:

Amendment \A*mend"ment\, n. [F. amendement, LL. amendamentum.]
   1. An alteration or change for the better; correction of a
      fault or of faults; reformation of life by quitting vices.
      [1913 Webster]

   2. In public bodies; Any alternation made or proposed to be
      made in a bill or motion by adding, changing,
      substituting, or omitting.
      [1913 Webster]

   3. (Law) Correction of an error in a writ or process.
      [1913 Webster]

   Syn: Improvement; reformation; emendation.
        [1913 Webster]

WordNet (r) 3.0 (2006):

amendment
    n 1: the act of amending or correcting
    2: a statement that is added to or revises or improves a
       proposal or document (a bill or constitution etc.)

Moby Thesaurus II by Grady Ward, 1.0:

85 Moby Thesaurus words for "amendment":
   Great Leap Forward, addendum, addition, advance, advancement,
   alteration, amelioration, ascent, attachment, bettering,
   betterment, bill, boost, calendar, change, change of allegiance,
   change of heart, change of mind, clause, companion bills amendment,
   correction, dragnet clause, editing, emendation, enacting clause,
   enhancement, enrichment, escalator clause, eugenics, euthenics,
   furtherance, headway, hold-up bill, improvement, joker, lift,
   melioration, mend, mending, motion, new birth, omnibus bill,
   paragraph, pickup, preferment, privileged question, progress,
   progression, promotion, proviso, question, rebirth, recension,
   reclamation, recovery, recrudescence, rectification, redaction,
   redemption, reform, reformation, regeneration, renascence, renewal,
   repair, rescript, rescription, restoration, revampment, revisal,
   revise, revised edition, revision, revival, rewrite, rewriting,
   rider, rise, saving clause, upbeat, uplift, upping, upswing,
   uptrend, upward mobility



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

AMENDMENT, legislation. An alteration or change of something proposed in a
bill.
     2. Either house of the legislature has a right to make amendments; but,
when so made, they must be sanctioned by the other house before they can
become a law. The senate has no power to originate any money bills, (q. v,)
but may propose and make amendments to such as have passed the House of
representatives. Vide Congress; Senate.
     3. The constitution of the United States, art. 5, and the constitutions
of some of the states, provide for their amendment. The provisions contained
in tho constitution of the United States, are as follows: "Congress,
whenever two-thirds of both houses shall deem it necessary, shall propose
amendments to this constitution, or, on the application of the legislatures
of two-thirds of the several states, shall call a convention for proposing
amendments, which, in either case, shall be valid, to all intents and
purposes, as part of this constitution, when ratified by the legislatures of
three-fourths of the several states, or by conventions in three-fourths
thereof, as the one or the other mode of ratification may be proposed by
Congress: Provided, that no amendment which may be made prior to the year
one thousand eight hundred and eight, shall, in any manner, affect the first
and fourth clauses in the ninth section of the first article; and that no
state, without its consent, shall be deprived of its equal suffrage in the
Senate."



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

AMENDMENT, practice. The correction, by allowance of the court, of an error
committed in the progress of a cause.
     2. Amendments at common law, independently of any statutory provision
on the subject, are in all cases in the discretion of the court, for the
furtherance of justice they may be made while the proceedings are in paper,
that is, until judgment is signed, and during the term in which it is
signed; for until the end of the term the proceedings are considered in
fieri, and consequently subject to the control of the court; 2 Burr. 756; 3
Bl. Com. 407; 1 Salk. 47; 2 Salk. 666 ; 8 Salk. 31; Co. Litt. 260; and even
after judgment is signed, and up to the latest period of the action,
amendment is, in most cases, allowable at the discretion of the court under
certain statutes passed for allowing amendments of the record; and in later
times the judges have been much more liberal than formerly, in the exercise
of this discretion. 3 McLean, 379; 1 Branch, 437; 9 Ala. 647. They may,
however, be made after the term, although formerly the rule was otherwise;
Co. Litt. 260, a; 3 Bl. Com. 407; and even after error brought, where there
has been a verdict in a civil or criminal case. 2 Serg. & R. 432, 3. A
remittitur damna may be allowed after error; 2 Dall. 184; 1 Yeates, 186;
Addis, 115, 116; and this, although error be brought on the ground of the
excess of damages remitted. 2 Serg. & R. 221. But the application must be
made for the remittitur in the court below, as the court of error must take
the record as they find it. 1 Serg. & R. 49. So, the death of the defendant
may be suggested after errer coram nobis. 1 Bin. 486; I Johns. Cases, 29;
Caines' Cases, 61. So by agreement of attorneys, the record may be amended
after error. 1 Bin. 75; 2 Binn. 169.
     3. Amendments are, however, always limited by due consideration of the
rights of the opposite party; and, when by the amendment he would be
prejudiced or exposed to unreasonable delay, it is not allowed. Vide Bac. Ab
Com. Dig. h.t.; Viner's. Ab. h.t.; 2 Arch. Pr. 200; Grah. Pt. 524; Steph.
Pl. 97; 2 Sell. Pr. 453; 3 Bl. Com. 406; Bouv. Inst. Index, h.t.