isopleth vs isarithm

isopleth and isarithm both are nouns.

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

As nouns, isopleth and isarithm are synonyms defined as:

isopleth and isarithm: a line drawn on a map connecting points having the same numerical value of some variable

Other synonyms of isopleth include isogram.

isopleth (noun)	isarithm (noun)
a line drawn on a map connecting points having the same numerical value of some variable	a line drawn on a map connecting points having the same numerical value of some variable