variometer

noun

1. Electricity. an instrument for measuring inductance, consisting essentially of an inductor with two or more coils whose relative position may be changed to vary the inductance.
2. an instrument for indicating a change in a component of a magnetic field vector, especially one related to the earth’s magnetic field.
3. Aeronautics. an instrument that indicates the rate of climb or descent.

noun

1. an instrument for measuring variations in a magnetic field, used esp for studying the magnetic field of the earth
2. electronics a variable inductor consisting of a movable coil mounted inside and connected in series with a fixed coil
3. a sensitive rate-of-climb indicator, used mainly in gliders