natural philosophy vs wave front

natural philosophy and wave front both are nouns.

Word	Noun	Adjective	Verb	Adverb
natural philosophy	Yes	No	No	No
wave front	Yes	No	No	No

natural philosophy (noun)	wave front (noun)
the science of matter and energy and their interactions	(physics) an imaginary surface joining all points in space that are reached at the same instant by a wave propagating through a medium
	all the points just reached by a wave as it propagates