aeronautics vs rigid

aeronautics is a noun but rigid is not a noun.

Word	Noun	Adjective	Verb	Adverb
aeronautics	Yes	No	No	No
rigid	No	Yes	No	No

aeronautics (noun)	rigid (noun)
the theory and practice of navigation through air or space

aeronautics (adjective)	rigid (adjective)
	designating an airship or dirigible having a form maintained by a stiff unyielding frame or structure
	incapable of or resistant to bending
	incapable of compromise or flexibility
	fixed and unmoving
	incapable of adapting or changing to meet circumstances