natural philosophy vs mechanical stress

natural philosophy and mechanical stress both are nouns.

Word	Noun	Adjective	Verb	Adverb
natural philosophy	Yes	No	No	No
mechanical stress	Yes	No	No	No

natural philosophy (noun)	mechanical stress (noun)
the science of matter and energy and their interactions	elastic stress (any deformation of a solid material) and viscous stress (the gradual changing of the deformation) combined.