dour vs persistent

dour and persistent both are adjectives.

Word	Noun	Adjective	Verb	Adverb
dour	No	Yes	No	No
persistent	No	Yes	No	No

As adjectives, dour and persistent are synonyms defined as:

Other synonyms of dour include dogged, pertinacious, tenacious, unyielding.

dour (adjective)	persistent (adjective)
showing a brooding ill humor	retained; not shed
stubbornly unyielding	never-ceasing
harshly uninviting or formidable in manner or appearance	stubbornly unyielding
	continually recurring to the mind