dun vs frustrate

dun is a noun but frustrate is not a noun.

Word	Noun	Adjective	Verb	Adverb
dun	Yes	Yes	Yes	No
frustrate	No	No	Yes	No

As verbs, dun and frustrate are synonyms defined as:

Other synonyms of dun include bedevil, crucify, rag, torment.

dun (noun)	frustrate (noun)
horse of a dull brownish grey color
a color or pigment varying around a light grey-brown color

dun (adjective)	frustrate (adjective)
of a dull greyish brown to brownish grey color

dun (verb)	frustrate (verb)
make a dun color	treat cruelly
cure by salting	hinder or prevent (the efforts, plans, or desires) of
persistently ask for overdue payment
treat cruelly