secret vs concealed

secret is a noun but concealed is not a noun.

Word	Noun	Adjective	Verb	Adverb
secret	Yes	Yes	No	No
concealed	No	Yes	No	No

secret (noun)	concealed (noun)
something that baffles understanding and cannot be explained
something that should remain hidden from others (especially information that is not to be passed on)
information known only to a special group

secret (adjective)	concealed (adjective)
the next to highest level of official classification for documents	hidden on any grounds for any motive
not open or public; kept private or not revealed	not accessible to view
having an import not apparent to the senses nor obvious to the intelligence; beyond ordinary understanding
not expressed
(of information) given in confidence or in secret
not openly made known
conducted with or marked by hidden aims or methods
designed to elude detection
indulging only covertly
hidden from general view or use
communicated covertly