rain gage vs udometer

rain gage and udometer both are nouns.

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

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

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

Other synonyms of rain gage include pluviometer, rain gauge.

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