Source : Webster's Revised Unabridged Dictionary (1913)

Tachymeter \Ta*chym"e*ter\, n. [Tachy- + -meter.]
   1. (Surveying) An instrument, esp. a transit or theodolite
      with stadia wires, for determining quickly the distances,
      bearings, and elevations of distant objects.

   2. A speed indicator; a tachometer.

Source : WordNet®

tachymeter
     n : a theodolite designed for rapid measurements [syn: {tacheometer}]