roundabout vs devious

roundabout is a noun but devious is not a noun.

Word	Noun	Adjective	Verb	Adverb
roundabout	Yes	Yes	No	No
devious	No	Yes	No	No

As adjectives, roundabout and devious are synonyms defined as:

Other synonyms of roundabout include circuitous.

roundabout (noun)	devious (noun)
a road junction at which traffic streams circularly around a central island
a large, rotating machine with seats for children to ride on for amusement

roundabout (adjective)	devious (adjective)
deviating from a straight course	deviating from a straight course
marked by obliqueness or indirection in speech or conduct	indirect in departing from the accepted or proper way; misleading
	characterized by insincerity or deceit; evasive