mail vs Dark Ages

mail and Dark Ages both are nouns.

Word	Noun	Adjective	Verb	Adverb
mail	Yes	No	Yes	No
Dark Ages	Yes	No	No	No

mail (noun)	Dark Ages (noun)
(Middle Ages) flexible armor made of interlinked metal rings	the period of history between classical antiquity and the Italian Renaissance
a conveyance that transports the letters and packages that are conveyed by the postal system
the system whereby messages are transmitted via the post office
the bags of letters and packages that are transported by the postal service
any particular collection of letters or packages that is delivered

mail (verb)	Dark Ages (verb)
cause to be directed or transmitted to another place
send via the postal service