1650s, "actually," from effective + -ly (2). From c. 1600 as "as a means of producing;" from 1825 as "so as to produce an effect."
Entries linking to effectively
effective adj.
late 14c., "serving to effect the intended purpose," from Old French effectif, from Latin effectivus "productive, effective," from effect-, stem of efficere "work out, accomplish" (see effect (n.)). Of military forces, "fit for action or duty," from 1680s.
-ly 2
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.