The Collaborative International Dictionary of English v.0.48:

Trial \Tri"al\, n. [From Try.]
   1. The act of trying or testing in any manner. Specifically:

      [1913 Webster]
      (a) Any effort or exertion of strength for the purpose of
          ascertaining what can be done or effected.
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                [I] defy thee to the trial of mortal fight.
                                                  --Milton.
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      (b) The act of testing by experience; proof; test.
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                Repeated trials of the issues and events of
                actions.                          --Bp. Wilkins.
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      (c) Examination by a test; experiment, as in chemistry,
          metallurgy, etc.
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   2. The state of being tried or tempted; exposure to suffering
      that tests strength, patience, faith, or the like;
      affliction or temptation that exercises and proves the
      graces or virtues of men.
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            Others had trial of cruel mockings and scourgings.
                                                  --Heb. xi. 36.
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   3. That which tries or afflicts; that which harasses; that
      which tries the character or principles; that which tempts
      to evil; as, his child's conduct was a sore trial.
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            Every station is exposed to some trials. --Rogers.
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   4. (Law) The formal examination of the matter in issue in a
      cause before a competent tribunal; the mode of determining
      a question of fact in a court of law; the examination, in
      legal form, of the facts in issue in a cause pending
      before a competent tribunal, for the purpose of
      determining such issue.
      [1913 Webster]

   Syn: Test; attempt; endeavor; effort; experiment; proof;
        essay. See Test, and Attempt.
        [1913 Webster]

WordNet (r) 3.0 (2006):

trial
    n 1: the act of testing something; "in the experimental trials
         the amount of carbon was measured separately"; "he called
         each flip of the coin a new trial" [syn: test, trial,
         run]
    2: trying something to find out about it; "a sample for ten days
       free trial"; "a trial of progesterone failed to relieve the
       pain" [syn: trial, trial run, test, tryout]
    3: the act of undergoing testing; "he survived the great test of
       battle"; "candidates must compete in a trial of skill" [syn:
       test, trial]
    4: (law) the determination of a person's innocence or guilt by
       due process of law; "he had a fair trial and the jury found
       him guilty"; "most of these complaints are settled before
       they go to trial"
    5: (sports) a preliminary competition to determine
       qualifications; "the trials for the semifinals began
       yesterday"
    6: an annoying or frustrating or catastrophic event; "his
       mother-in-law's visits were a great trial for him"; "life is
       full of tribulations"; "a visitation of the plague" [syn:
       trial, tribulation, visitation]

The Devil's Dictionary (1881-1906):

TRIAL, n.  A formal inquiry designed to prove and put upon record the
blameless characters of judges, advocates and jurors.  In order to
effect this purpose it is necessary to supply a contrast in the person
of one who is called the defendant, the prisoner, or the accused.  If
the contrast is made sufficiently clear this person is made to undergo
such an affliction as will give the virtuous gentlemen a comfortable
sense of their immunity, added to that of their worth.  In our day the
accused is usually a human being, or a socialist, but in mediaeval
times, animals, fishes, reptiles and insects were brought to trial.  A
beast that had taken human life, or practiced sorcery, was duly
arrested, tried and, if condemned, put to death by the public
executioner.  Insects ravaging grain fields, orchards or vineyards
were cited to appeal by counsel before a civil tribunal, and after
testimony, argument and condemnation, if they continued _in
contumaciam_ the matter was taken to a high ecclesiastical court,
where they were solemnly excommunicated and anathematized.  In a
street of Toledo, some pigs that had wickedly run between the
viceroy's legs, upsetting him, were arrested on a warrant, tried and
punished.  In Naples and ass was condemned to be burned at the stake,
but the sentence appears not to have been executed.  D'Addosio relates
from the court records many trials of pigs, bulls, horses, cocks,
dogs, goats, etc., greatly, it is believed, to the betterment of their
conduct and morals.  In 1451 a suit was brought against the leeches
infesting some ponds about Berne, and the Bishop of Lausanne,
instructed by the faculty of Heidelberg University, directed that some
of "the aquatic worms" be brought before the local magistracy.  This
was done and the leeches, both present and absent, were ordered to
leave the places that they had infested within three days on pain of
incurring "the malediction of God."  In the voluminous records of this
_cause celebre_ nothing is found to show whether the offenders braved
the punishment, or departed forthwith out of that inhospitable
jurisdiction.