mid-15c., from well (adv.) + past participle of inform (v.).
Entries linking to well-informed
well adv.
"in a satisfactory manner," Old English wel "abundantly, very, very much; indeed, to be sure; with good reason; nearly, for the most part," from Proto-Germanic *wel- (source also of Old Saxon wela, Old Norse vel, Old Frisian wel, Dutch wel, Old High German wela, German wohl, Gothic waila "well"), from PIE root *wel- (2) "to wish, will" (source also of Sanskrit prati varam "at will," Old Church Slavonic vole "well," Welsh gwell "better," Latin velle "to wish, will," Old English willan "to wish;" see will (v.)).
Also used in Old English as an interjection and an expression of surprise. The adjective was in Old English in the sense "in good fortune, happy," from the adverb; sense of "satisfactory" is from late 14c.; "agreeable to wish or desire" is from mid-15c.; "in good health, not ailing" is from 1550s. Well-to-do "prosperous" is recorded by 1794.
inform v.
early 14c., "to train or instruct in some specific subject," from Old French informer, enformer "instruct, teach" (13c.) and directly from Latin informare "to shape, give form to, delineate," figuratively "train, instruct, educate," from in- "into" (from PIE root *en "in") + formare "to form, shape," from forma "form" (see form (n.)). In early use also enform until c. 1600. Sense of "report facts or news, communicate information to" first recorded late 14c. Related: Informed; informing.