Wordnet 3.0
NOUN (1)
1.
a measuring instrument for detecting and measuring the intensity and direction and duration of movements of the ground (as an earthquake);
The Collaborative International Dictionary of English v.0.48:
Seismograph \Seis"mo*graph\, n. [Gr. ??? an earthquake +
-graph.] (Physics)
An apparatus for registering the shocks and undulatory
motions of earthquakes.
[1913 Webster]
WordNet (r) 3.0 (2006):
seismograph
n 1: a measuring instrument for detecting and measuring the
intensity and direction and duration of movements of the
ground (as an earthquake)