Source : Webster's Revised Unabridged Dictionary (1913)

Piecework \Piece"work`\, n.
   Work done by the piece or job; work paid for at a rate based
   on the amount of work done, rather than on the time employed.

         The reaping was piecework, at so much per acre. --R.
                                                  Jefferies.

Source : WordNet®

piecework
     n : work paid for according to the quantity produced