isobar vs isarithm

isobar and isarithm both are nouns.

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

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

isobar: (meteorology)an isogram connecting points having equal barometric pressure at a given time
isarithm: a line drawn on a map connecting points having the same numerical value of some variable

Other hypernyms of isobar include isogram, isopleth.

isobar (noun)	isarithm (noun)
(meteorology)an isogram connecting points having equal barometric pressure at a given time	a line drawn on a map connecting points having the same numerical value of some variable