secular vs impious

secular is a noun but impious is not a noun.

Word	Noun	Adjective	Verb	Adverb
secular	Yes	Yes	No	No
impious	No	Yes	No	No

secular (noun)	impious (noun)
someone who is not a clergyman or a professional person

secular (adjective)	impious (adjective)
of or relating to clergy not bound by monastic vows	lacking piety or reverence for a god
not concerned with or devoted to religion	lacking due respect or dutifulness
characteristic of or devoted to the temporal world as opposed to the spiritual world
of or relating to the doctrine that rejects religion and religious considerations
characteristic of those who are not members of the clergy