rain gage vs pluviometer

rain gage and pluviometer both are nouns.

Word	Noun	Adjective	Verb	Adverb
rain gage	Yes	No	No	No
pluviometer	Yes	No	No	No

As nouns, rain gage and pluviometer are synonyms defined as:

rain gage and pluviometer: gauge consisting of an instrument to measure the quantity of precipitation

Other synonyms of rain gage include rain gauge, udometer.

rain gage (noun)	pluviometer (noun)
gauge consisting of an instrument to measure the quantity of precipitation	gauge consisting of an instrument to measure the quantity of precipitation