an instrument for graphically recording oscillatory variations, as in alternating currents.
Origin of ondograph
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
an instrument for producing a graphical recording of an alternating current by measuring the charge imparted to a capacitor at different points in the cycle
Word Origin for ondograph
C20: from French, from onde wave + -graph
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012