gas meter vs gasometer

gas meter and gasometer both are nouns.

Word	Noun	Adjective	Verb	Adverb
gas meter	Yes	No	No	No
gasometer	Yes	No	No	No

As nouns, gas meter and gasometer are synonyms defined as:

gas meter and gasometer: a meter for measuring the amount of gas flowing through a particular pipe

gas meter (noun)	gasometer (noun)
a meter for measuring the amount of gas flowing through a particular pipe	a large gas-tight spherical or cylindrical tank for holding gas to be used as fuel
	a meter for measuring the amount of gas flowing through a particular pipe