fluent vs fluid

fluent is not a noun while fluid is a noun.

Word	Noun	Adjective	Verb	Adverb
fluent	No	Yes	No	No
fluid	Yes	Yes	No	No

As adjectives, fluent and fluid are synonyms defined as:

Other synonyms of fluent include liquid, smooth.

fluent (noun)	fluid (noun)
	continuous amorphous matter that tends to flow and to conform to the outline of its container: a liquid or a gas
	a substance that is fluid at room temperature and pressure

fluent (adjective)	fluid (adjective)
expressing yourself readily, clearly, effectively	subject to change; variable
smooth and unconstrained in movement	in cash or easily convertible to cash
	smooth and unconstrained in movement
	characteristic of a fluid; capable of flowing and easily changing shape
	affording change (especially in social status)