Source : Webster's Revised Unabridged Dictionary (1913)

Sinking \Sink"ing\,
   a. & n. from {Sink}.

   {Sinking fund}. See under {Fund}.

   {Sinking head} (Founding), a riser from which the mold is fed
      as the casting shrinks. See {Riser}, n., 4.

   {Sinking pump}, a pump which can be lowered in a well or a
      mine shaft as the level of the water sinks.