fortunately (adv.)

late 14c., "having good fortune; bringing good fortune," from Latin fortunatus "prospered, prosperous; lucky, happy," past participle of fortunare "to make prosperous," from fortuna (see fortune). Fortunate Islands "mythical abode of the blessed dead, in the Western Ocean" (early 15c.; late 14c. as Ilondes of fortune) translates Latin Fortunatae Insulae.

common adverbial suffix, forming from adjectives adverbs signifying "in a manner denoted by" the adjective, Middle English, from Old English -lice, from Proto-Germanic *-liko- (cognates: Old Frisian -like, Old Saxon -liko, Dutch -lijk, Old High German -licho, German -lich, Old Norse -liga, Gothic -leiko); see -ly (1). Cognate with lich, and identical with like (adj.).

Weekley notes as "curious" that Germanic uses a word essentially meaning "body" for the adverbial formation, while Romanic uses one meaning "mind" (as in French constamment from Latin constanti mente). The modern English form emerged in late Middle English, probably from influence of Old Norse -liga.