Source : Webster's Revised Unabridged Dictionary (1913)

Pieta \Pi*e*t[`a]"\ (p[-e]*[asl]*t[aum]"), n. [It.] (Fine Arts)
   A representation of the dead Christ, attended by the Virgin
   Mary or by holy women and angels. --Mollett.

Source : WordNet®

pieta
     n : a representation of the Virgin Mary mourning over the dead
         body of Jesus