regal vs purple

regal is not a noun while purple is a noun.

Word	Noun	Adjective	Verb	Adverb
regal	No	Yes	No	No
purple	Yes	Yes	Yes	No

As adjectives, regal and purple are synonyms defined as:

Other synonyms of regal include imperial, majestic, royal.

regal (noun)	purple (noun)
	(Roman Catholic Church) official dress of a cardinal; so named after the Tyrial purple color of the robes
	a color between red and blue
	(in ancient Rome) position of imperial status

regal (adjective)	purple (adjective)
belonging to or befitting a supreme ruler	of a color intermediate between red and blue
	belonging to or befitting a supreme ruler
	excessively elaborate or showily expressed

regal (verb)	purple (verb)
	color purple
	become purple