unscheduled vs special

unscheduled is not a noun while special is a noun.

Word	Noun	Adjective	Verb	Adverb
unscheduled	No	Yes	No	No
special	Yes	Yes	No	No

unscheduled (noun)	special (noun)
	a special offering (usually temporary and at a reduced price) that is featured in advertising
	a television production that features a particular person or work or topic
	a dish or meal given prominence in e.g. a restaurant

unscheduled (adjective)	special (adjective)
not scheduled or not on a regular schedule	for a special service or occasion
	first and most important
	adapted to or reserved for a particular purpose
	having a specific function or scope
	surpassing what is common or usual or expected
	added to a regular schedule
	unique or specific to a person or thing or category