noun.
An instrument that registers or graphically records time intervals such as the duration of an event.
The Century Dictionary and Cyclopedia
noun.
A chronogram.
noun.
An instrument for recording the exact instant in which an event occurs.
noun.
An instrument for measuring a small interval of time.
the GNU version of the Collaborative International Dictionary of English
noun.
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.