What does "absolute altimeter" mean?

A type of altimeter which measures vertical distance to the surface below, using radio, radar, sonic, laser, or capacitive technology.

What is a synonym for "absolute altimeter"?

Common synonyms include: direction finder, instrument.

/ˈæb.səˌlut/ noun

noun ·Rare ·Advanced level

Noun

1
A type of altimeter which measures vertical distance to the surface below, using radio, radar, sonic, laser, or capacitive technology.