mechanical stress vs natural philosophy

mechanical stress and natural philosophy both are nouns.

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

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