groovy vs smashing

groovy is not a noun while smashing is a noun.

Word	Noun	Adjective	Verb	Adverb
groovy	No	Yes	No	No
smashing	Yes	Yes	No	No

As adjectives, groovy and smashing are synonyms defined as:

Other synonyms of groovy include bang-up, bully, corking, cracking, dandy, great, keen, neat, nifty, not bad, old, peachy, slap-up, swell.

groovy (noun)	smashing (noun)
	the act of breaking something into small pieces

groovy (adjective)	smashing (adjective)
(British informal) very chic	excellent
excellent