Source : Webster's Revised Unabridged Dictionary (1913)

Plaintiff \Plain"tiff\, n. [F. plaintif making complaint,
   plaintive; in Old French equiv. to plaignant complainant,
   prosecutor, fr. plaindre. See {Plaint}, and cf. {Plaintive}.]
   (Law)
   One who commences a personal action or suit to obtain a
   remedy for an injury to his rights; -- opposed to
   {defendant}.

Plaintiff \Plain"tiff\, a.
   See {Plaintive}. [Obs.] --Prior.

Source : WordNet®

plaintiff
     n : a person who brings an action in a court of law [syn: {complainant}]
         [ant: {defendant}]