isobase vs isarithm

isobase and isarithm both are nouns.

Word	Noun	Adjective	Verb	Adverb
isobase	Yes	No	No	No
isarithm	Yes	No	No	No

As nouns, isarithm is a hypernym of isobase; that is, isarithm is a word with a broader meaning than isobase:

isobase: a line drawn on a map or chart connecting places of equal or constant land upheaval.
isarithm: a line drawn on a map connecting points having the same numerical value of some variable

Other hypernyms of isobase include isogram, isopleth.

isobase (noun)	isarithm (noun)
a line drawn on a map or chart connecting places of equal or constant land upheaval.	a line drawn on a map connecting points having the same numerical value of some variable