feedback vs feed back

feedback is a noun but feed back is not a noun.

Word	Noun	Adjective	Verb	Adverb
feedback	Yes	No	No	No
feed back	No	No	Yes	No

feedback (noun)	feed back (noun)
response to an inquiry or experiment
the process in which part of the output of a system is returned to its input in order to regulate its further output

feedback (verb)	feed back (verb)
	respond to a query or outcome
	submit (information) again to a program or automatic system