Thermophone
Pronunciation : Ther"mo*phone
Part of Speech : n.
Definition : 1. A portable form of telethermometer, using a telephone in connection with a differential thermometer.
2. A telephone involving heat effects, as changes in temperature (hence in length) due to pulsations of the line current in a fine wire connected with the receiver diaphragm.
[Thermo- + phone.]
Source : Webster's Unabridged Dictionary, 1913