throwaway vs cast-off

throwaway is a noun but cast-off is not a noun.

Word	Noun	Adjective	Verb	Adverb
throwaway	Yes	Yes	No	No
cast-off	No	Yes	No	No

As adjectives, throwaway and cast-off are synonyms defined as:

Other synonyms of throwaway include discarded, thrown-away.

throwaway (noun)	cast-off (noun)
an advertisement (usually printed on a page or in a leaflet) intended for wide distribution
words spoken in a casual way with conscious under-emphasis
(sometimes offensive) a homeless boy who has been abandoned and roams the streets

throwaway (adjective)	cast-off (adjective)
intended to be thrown away after use	thrown away
thrown away