empiricism vs empirical

empiricism is a noun but empirical is not a noun.

Word	Noun	Adjective	Verb	Adverb
empiricism	Yes	No	No	No
empirical	No	Yes	No	No

empiricism (noun)	empirical (noun)
the application of empirical methods in any art or science
medical practice and advice based on observation and experience in ignorance of scientific findings
(philosophy) the doctrine that knowledge derives from experience

empiricism (adjective)	empirical (adjective)
	derived from experiment and observation rather than theory
	relying on medical quackery