The Collaborative International Dictionary of English v.0.48:

Monition \Mo*ni"tion\, n. [F., fr. L. monitio, from monere to
   warn, bring to mind; akin to E. mind. See Mind, and cf.
   Admonish, Money, Monster.]
   1. Instruction or advice given by way of caution; an
      admonition; a warning; a caution.
      [1913 Webster]

            Sage monitions from his friends.      --Swift.
      [1913 Webster]

   2. Information; indication; notice; advice.
      [1913 Webster]

            We have no visible monition of . . . other periods,
            such as we have of the day by successive light and
            darkness.                             --Holder.
      [1913 Webster]

   3. (Admiralty Practice) A process in the nature of a summons
      to appear and answer.
      [1913 Webster]

   4. (Eccl. Law) An order monishing a party complained against
      to obey under pain of the law. --Shipley.
      [1913 Webster]

WordNet (r) 3.0 (2006):

monition
    n 1: a firm rebuke [syn: admonition, admonishment,
         monition]
    2: cautionary advice about something imminent (especially
       imminent danger or other unpleasantness); "a letter of
       admonition about the dangers of immorality"; "the warning was
       to beware of surprises"; "his final word of advice was not to
       play with matches" [syn: admonition, monition, warning,
       word of advice]
    3: a summons issued after the filing of a libel or claim
       directing all parties concerned to show cause why the
       judgment asked for should not be granted [syn: monition,
       process of monition]

Moby Thesaurus II by Grady Ward, 1.0:

68 Moby Thesaurus words for "monition":
   admonishment, admonition, advice, advising, advocacy, alarm,
   alerting, briefing, caution, cautioning, caveat, certiorari,
   citation, clue, consultation, council, counsel, cue, determent,
   deterrence, deterrent example, direction, example, exhortation,
   expostulation, final notice, final warning, forewarning,
   frightening off, garnishment, guidance, habeas corpus, hint,
   hortation, idea, instruction, intimidation, lesson, moral, notice,
   notification, object lesson, office, opinion, parley, passing word,
   pointer, proposal, recommendation, remonstrance, steer, subpoena,
   suggestion, summons, talking out of, thought, threat, tip, tip-off,
   ultimatum, venire, venire de novo, venire facias, verbum sapienti,
   warning, warning piece, whisper, writ of summons



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

MONITION, practice. In those courts which use the civil law process, (as the
court of admiralty, whose proceedings are, under the provisions of the acts
of congress, to be according to the course of the civil law,) it is a
process in the nature of a summons; it is either, general, special, or
mixed.
     2.-1. The general monition is a citation or summons to all persons
interested, or, as is commonly said, to the whole world, to appear and show
cause why the libel filed in the case should not be sustained, and the
prayer of relief granted. This is adopted in prize cases, admiralty suits
for forfeitures, and other suits in rem, when no particular individuals are
summoned to answer. In such cases the taking possession of the property
libeled, and this general citation or nomination, served according to law,
are considered constructive notice to the world of the pendency of the suit;
and the judgment rendered thereupon is conclusive upon the title of the
property which may be affected. In form, the monition is a warrant of the
court, in an admiralty cause, directed to the marshal or his deputy,
commanding him in the name of the president of the United States, to give
public notice, by advertisements in such newspapers as the court may select,
and by notification to be posted in public places, that a libel has been
filed in a certain admiralty cause pending, and of the time and place
appointed for the trial. A brief statement of the allegations in the libel
is usually contained in the monition. The monition is served in the manner
directed in the warrant.
     3.-2. A special monition is a similar warrant, directed to the
marshal or his deputy, requiring him to give special notice to certain
persons, named in the warrant, of the pendency of the suit, the grounds of
it, and the time and place of trial. It is served by delivery of a copy of
the warrant, attested by the officer, to each one of the adverse parties, or
by leaving the same at his usual place of residence; but the service should
be personal if possible. Clark. Prax. tit. 21; Dunl. Admr. Pr. 135.
     4.-3. A mixed monition is one which contains directions for a general
monition to all persons interested, and a special summons to particular
persons named in the warrant. This is served by newspaper advertisements, by
notifications posted in public places, and by delivery of a copy attested by
the officer to each person specially named, or by leaving it at his usual
place of residence. See Dunlap's Adm. Pr. Index, h.t.; Bett's Adm. Pr.
Index, h.t.