Source : Webster's Revised Unabridged Dictionary (1913)

Dumpy level \Dump"y lev"el\ (Surv.)
   A level having a short telescope (hence its name) rigidly
   fixed to a table capable only of rotatory movement in a
   horizontal plane. The telescope is usually an inverting one.
   It is sometimes called the {Troughton level}, from the name
   of the inventor, and a variety improved by one Gavatt is
   known as the {Gavatt level}.

Source : WordNet®

Dumpy level
     n : a surveyor's level having a short telescope fixed to a
         horizontally rotating table and a spirit level