magnitude vs mensurable

magnitude is a noun but mensurable is not a noun.

Word	Noun	Adjective	Verb	Adverb
magnitude	Yes	No	No	No
mensurable	No	Yes	No	No

magnitude (noun)	mensurable (noun)
the property of relative size or extent (whether large or small)
relative importance
a number assigned to the ratio of two quantities; two quantities are of the same order of magnitude if one is less than 10 times as large as the other; the number of magnitudes that the quantities differ is specified to within a power of 10

magnitude (adjective)	mensurable (adjective)
	capable of being measured
	having notes of fixed rhythmic value