What does Voltmeter mean?
A voltmeter is an electronic instrument used to measure potential between any two points in an electric or electronic circuit in volts. A voltmeter can display readings in analog (a pointer across a scale in fraction of the voltage of the circuit) or digital (shows voltage directly as numerals) form. A voltmeter can also be used to measure AC, DC as well as RF currents.
Techopedia explains Voltmeter
Generally, an analog voltmeter has an accuracy of up to a few fractions of a given full scale, and it is used to measure voltages from a fraction of a volt to a couple of thousand volts. In contrast, a digital voltmeter has a higher accuracy and is normally used for very small voltage measurements in laboratories and electronic devices. Meters consisting of amplifiers can record very minute voltages, and their accuracy is in nanovolts. A voltmeter can be mounted to a transformer and other such huge voltage devices, and it can also be portable in the form of digital multimeters.