concrete vs existent

concrete is a noun but existent is not a noun.

Word	Noun	Adjective	Verb	Adverb
concrete	Yes	Yes	Yes	No
existent	No	Yes	No	No

concrete (noun)	existent (noun)
a strong hard building material composed of sand and gravel and cement and water

concrete (adjective)	existent (adjective)
capable of being perceived by the senses; not abstract or imaginary	having existence or being or actuality
formed by the coalescence of particles	being or occurring in fact or actuality; having verified existence; not illusory
	presently existing in fact and not merely potential or possible

concrete (verb)	existent (verb)
form into a solid mass; coalesce
cover with cement