udometer vs rain gauge

udometer and rain gauge both are nouns.

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

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

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

Other synonyms of udometer include pluviometer, rain gage.

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