Entry 1 sense Webster, 1913 Phrenograph /(frē"nō̇*grȧf)/ · Phre·no·graph · IPA 01 n. An instrument for registering the movements of the diaphragm, or midriff, in respiration. 1. An instrument for registering the movements of the diaphragm, or midriff, in respiration.(Physiol.)