Here's how it's used in different contexts:
* Metrology: The science of measurement.
* Metronome: A device that marks time in music.
* Metro: Short for "Metropolitan," referring to a city or its surrounding area.
* Metropolitan: Of or relating to a large city or its surrounding area.
* Metropolis: A large, important city.
So, depending on the context, "metro" can refer to measurement, a large city, or something related to a large city.