The Collaborative International Dictionary of English v.0.48:

Plead \Plead\, v. t. [imp. & p. p. Pleaded (colloq. Pleador
   Pled); p. pr. & vb. n. Pleading.] [OE. pleden, plaiden,
   OF. plaidier, F. plaider, fr. LL. placitare, fr. placitum.
   See Plea.]
   1. To argue in support of a claim, or in defense against the
      claim of another; to urge reasons for or against a thing;
      to attempt to persuade one by argument or supplication; to
      speak by way of persuasion; as, to plead for the life of a
      criminal; to plead with a judge or with a father.
      [1913 Webster]

            O that one might plead for a man with God, as a man
            pleadeth for his neighbor!            --Job xvi. 21.
      [1913 Webster]

   2. (Law) To present an answer, by allegation of fact, to the
      declaration of a plaintiff; to deny the plaintiff's
      declaration and demand, or to allege facts which show that
      ought not to recover in the suit; in a less strict sense,
      to make an allegation of fact in a cause; to carry on the
      allegations of the respective parties in a cause; to carry
      on a suit or plea. --Blackstone. Burrill. Stephen.
      [1913 Webster]

   3. To contend; to struggle. [Obs.] --Chaucer.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pleading \Plead"ing\, n.
   The act of advocating, defending, or supporting, a cause by
   arguments.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pleading
    adj 1: begging [syn: beseeching, pleading, imploring]
           [ant: imperative]
    n 1: (law) a statement in legal and logical form stating
         something on behalf of a party to a legal proceeding

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "pleading":
   adjuratory, answer, appealing, argument, argumentum, bar, begging,
   beseeching, case, cons, consideration, counsel, counterstatement,
   defense, demurrer, denial, elenchus, entreating, exception,
   ignoratio elenchi, imploring, legal profession, objection,
   plaidoyer, plea, pleadings, precative, precatory, pros,
   pros and cons, reason, rebuttal, refutation, reply, representation,
   response, riposte, special demurrer, special pleading,
   statement of defense, talking point



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

PLEADING, practice. The statement in a logical, and legal form, of the facts
which constitute the plaintiff's cause of action, or the defendant's ground
of defence; it is the formal mode of alleging that on the record, which
would be the support, or the defence of the party in evidence. 8 T. R. 159;
Dougl. 278; Com. Dig. Pleader, A; Bac. Abr. Pleas and Pleading; Cowp. 682-3.
Or in the language of Lord Coke, good pleading consists in good matter
pleaded in good form, in apt time, and due order. Co. Lit. 303. In a general
sense, it is that which either party to a suit at law alleges for himself in
a court, with respect to the subject-matter of the cause, and the mode in
which it is carried on, including the demand which is made by the plaintiff;
but in strictness, it is no more than setting forth those facts or arguments
which show the justice or legal sufficiency of the plaintiff's demand, and
the defendant's defence, without including the statement of the demand
itself, which is contained in the declaration or count. Bac. Abr. Pleas and
Pleading.
     2. The science of pleading was designed only to render the facts of
each party's case plain and intelligible, and to bring the matter in dispute
between them to judgment. Steph. Pl. 1. It is, as has been well observed,
admirably calculated for analyzing a cause, and extracting, like the roots
of an equation, the true points in dispute; and referring them with all
imaginable simplicity, to the court and jury. 1 Hale's C. L. 301, n
     3. The parts of pleading have been considered as arrangeable under two
heads; first, the regular, or those which occur, in the ordinary course of a
suit; and secondly, the irregular, or collateral, being those which are
occasioned by mistakes in the pleadings on either side.
     4. The regular parts are, 1st. The declaration or count. 2d. The plea,
which is either to the jurisdiction of the court, or suspending the action,
a's in the case of a parol demurrer, or in abatement, or in bar of the
action, or in replevin, an avowry or cognizance. 3d. The replication, and,
in case of an evasive plea, a new assignment, or in replevin the plea in bar
to the avowry or cognizance. 4th. The rejoinder, or, in replevin, the
replication to the plea in bar. 5th. The sur-rejoinder, being in replevin,
the rejoinder. 6th. The rebutter. 7th. The sur-rebutter. Vin. Abr. Pleas and
Pleading, C; Bac. Abr. Pleas and Pleadings, A. 8th. Pleas puis darrein
continuance, when the matter of defence arises pending the suit.
     6. The irregular or collateral parts of Pleading are stated to be, 1st.
Demurrers to any art of the pleadings above mentioned. 2dly. Demurrers to
evidence given at trials. 3dly. Bills of exceptions. 4thly. Pleas in scire
facias. And, 5thly. Pleas in error. Vin. Abr. Pleas and Pleadings, C.; Bouv.
Inst. Index, h.t.



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

PLEADING, SPECIAL. By special pleading is meant the allegation of special or
new matter, as distinguished from a direct denial of matter previously
alleged on the opposite side. Gould on Pl. c. 1, s. 18.