Plain English Meaning
A meter that measures very tiny amounts of electrical pressure — the kind that are too small to register on a regular voltmeter.
Full Definition
An electrical test instrument that measures very small voltages, expressed in millivolts (thousandths of a volt). In aircraft maintenance it is commonly used to read the low-level signals produced by thermocouples in cylinder head temperature and exhaust gas temperature systems.
Context Anchor
Seen in aircraft maintenance when checking small electrical signals in wires, sensors, or test equipment.
Derivation
Built from three parts: 'milli-' (Latin for one-thousandth), 'volt' (named after Alessandro Volta, the inventor of the battery), and 'meter' (Greek 'metron', meaning 'measure'). So literally: an instrument that measures thousandths of a volt.
Why Pilots Care
Correct millivolt readings confirm that temperature sensors deliver accurate data, which supports safe engine monitoring and prevents undetected overheating.
Intuition Check
A millivoltmeter does not measure a different kind of electricity; it measures the same thing as a voltmeter, but on a much smaller scale.
Example Sentence 1
The technician used a millivoltmeter to check the output of the cylinder head temperature thermocouple.
Example Sentence 2
A steady reading on the millivoltmeter during the engine run-up verified that the temperature indicator circuit was functioning properly.