Source : Webster's Revised Unabridged Dictionary (1913)

Alto-rilievo \Al"to-ri*lie*vo\, n.; pl. {Alto-rilievos}. [It.]
   (Sculp.)
   High relief; sculptured work in which the figures project
   more than half their thickness; as, this figure is an
   alto-rilievo or in alto-rilievo.

   Note: When the figure stands only half out, it is called
         mezzo-rilievo, demi-rilievo, or medium relief; when its
         projection is less than one half, basso-rilievo,
         bas-relief, or low relief.