Definition of "millivoltmeter" []

• In electricity, a direct-reading instrument for the measurement of small differences of potential, in which the scale is graduated to read in thousandths of a volt. (noun)

The Century Dictionary (Public Domain)

• "If only one instrument, such as a millivoltmeter, is available, and there is no standard couple at hand, the new couple may be calibrated over a wide range of temperatures by the use of the following standards:"
• "I usually use my Boonton RF millivoltmeter, which has way more sensitivity than a regular diode detector RF probe with a DVM or VTVM, although -70 dBm sensitivity isn't needed, either."
• "... inside of a millivoltmeter, which seems to record its measurements on a soot-coated wheel marked with the hours."