*oscillograph*

n. [ L. oscillare to swing + -graph. ] (Elec.) An apparatus for recording or indicating alternating-current wave forms or other electrical oscillations, especially of voltages or currents; it usually consists of a galvanometer with strong field, in which the mass of the moving part is very small and frequency of vibration very high. -- Os`cil*lo*graph"ic a. [Webster 1913 Suppl.]