rest mass vs natural philosophy

rest mass and natural philosophy both are nouns.

Word	Noun	Adjective	Verb	Adverb
rest mass	Yes	No	No	No
natural philosophy	Yes	No	No	No

rest mass (noun)	natural philosophy (noun)
(physics) the mass of a body as measured when the body is at rest relative to an observer, an inherent property of the body	the science of matter and energy and their interactions