densitometry vs mensuration

densitometry and mensuration both are nouns.

Word	Noun	Adjective	Verb	Adverb
densitometry	Yes	No	No	No
mensuration	Yes	No	No	No

As nouns, mensuration is a hypernym of densitometry; that is, mensuration is a word with a broader meaning than densitometry:

densitometry: measuring the optical density of a substance by shining light on it and measuring its transmission
mensuration: the act or process of assigning numbers to phenomena according to a rule

Other hypernyms of densitometry include measure, measurement, measuring.

densitometry (noun)	mensuration (noun)
measuring the optical density of a substance by shining light on it and measuring its transmission	the act or process of assigning numbers to phenomena according to a rule