gayly vs happily

gayly and happily both are adverbs.

Word	Noun	Adjective	Verb	Adverb
gayly	No	No	No	Yes
happily	No	No	No	Yes

As adverbs, gayly and happily are synonyms defined as:

Other synonyms of gayly include blithely, jubilantly, merrily, mirthfully.

gayly (adverb)	happily (adverb)
in a joyous manner	in an unexpectedly lucky way
	in a joyous manner