union vs closed

union is a noun but closed is not a noun.

Word	Noun	Adjective	Verb	Adverb
union	Yes	Yes	No	No
closed	No	Yes	No	No

union (noun)	closed (noun)
the act of making or becoming a single unit
the act of pairing a male and female for reproductive purposes
a device on a national flag emblematic of the union of two or more sovereignties (typically in the upper inner corner)
the occurrence of a uniting of separate parts
an organization of employees formed to bargain with the employer
a political unit formed from previously independent people or organizations
a set containing all and only the members of two or more given sets
healing process involving the growing together of the edges of a wound or the growing together of broken bones
the state of being joined or united or linked
the state of being a married couple voluntarily joined for life (or until divorce)

union (adjective)	closed (adjective)
of trade unions	not open or affording passage or access
	(set theory) of an interval that contains both its endpoints
	used especially of mouth or eyes
	not open
	blocked against entry
	not open to the general public
	with shutters closed
	requiring union membership
	not having an open mind