Source : Webster's Revised Unabridged Dictionary (1913)

Chronograph \Chron"o*graph\, n. [Gr. ? time + -graph: cf. F.
   chronographe.]
   1. An instrument for measuring or recording intervals of
      time, upon a revolving drum or strip of paper moved by
      clockwork. The action of the stylus or pen is controlled
      by electricity.

   2. Same as {Chronogram}, 1. [R.]

   3. A chronoscope.

Source : WordNet®

chronograph
     n : an accurate timer for recording time