Source : Webster's Revised Unabridged Dictionary (1913)

Plead \Plead\, v. t.
   1. To discuss, defend, and attempt to maintain by arguments
      or reasons presented to a tribunal or person having
      uthority to determine; to argue at the bar; as, to plead a
      cause before a court or jury.

            Every man should plead his own matter. --Sir T.
                                                  More.

   Note: In this sense, argue is more generally used by lawyers.

   2. To allege or cite in a legal plea or defense, or for
      repelling a demand in law; to answer to an indictment; as,
      to plead usury; to plead statute of limitations; to plead
      not guilty. --Kent.

   3. To allege or adduce in proof, support, or vendication; to
      offer in excuse; as, the law of nations may be pleaded in
      favor of the rights of ambassadors. --Spenser.

            I will neither plead my age nor sickness, in excuse
            of faults.                            --Dryden.

Plead \Plead\, v. t. [imp. & p. p. {Pleaded} (colloq. {Plead}or
   {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.

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

   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.

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

Plead \Plead\, v. t. [imp. & p. p. {Pleaded} (colloq. {Plead}or
   {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.

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

   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.

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

Source : WordNet®

plead
     v 1: appeal or request earnestly; "I pleaded with him to stop"
     2: offer as an excuse or plea; "She was pleading insanity"
     3: enter a plea, as in courts of law; "She pleaded not guilty"
     4: make an allegation in an action or other legal proceeding,
        especially answer the previous pleading of the other party
        by denying facts therein stated or by alleging new facts
     [also: {pled}]