bathymeter vs bathometer

bathymeter and bathometer both are nouns.

Word	Noun	Adjective	Verb	Adverb
bathymeter	Yes	No	No	No
bathometer	Yes	No	No	No

As nouns, bathymeter and bathometer are synonyms defined as:

bathymeter and bathometer: an instrument that measures the depth of water

bathymeter (noun)	bathometer (noun)
an instrument that measures the depth of water	an instrument that measures the depth of water