sad vs glad

sad is not a noun while glad is a noun.

Word	Noun	Adjective	Verb	Adverb
sad	No	Yes	No	No
glad	Yes	Yes	No	No

sad (noun)	glad (noun)
	any of numerous plants of the genus Gladiolus native chiefly to tropical and South Africa having sword-shaped leaves and one-sided spikes of brightly colored funnel-shaped flowers; widely cultivated

sad (adjective)	glad (adjective)
experiencing or showing sorrow or unhappiness	showing or causing joy and pleasure; especially made happy
bad; unfortunate	cheerful and bright
of things that make you feel sad	feeling happy appreciation
	eagerly disposed to act or to be of service