"in a satisfactory manner," Old English wel, common Germanic (cf. Old Saxon wela, Old Norse vel, Old Frisian wel, Dutch wel, Old High German wela, German wohl, Gothic waila "well"), from PIE *wel-, *wol- (cf. 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. Well-to-do "prosperous" is recorded from 1825.
"to spring, rise, gush," Old English wiellan (Anglian wællan), causative of weallan "to boil, bubble up" (class VII strong verb; past tense weoll, past participle weallen), from Proto-Germanic *wal-, *wel- "roll" (cf. Old Saxon wallan, Old Norse vella, Old Frisian walla, Old High German wallan, German wallen, Gothic wulan "to bubble, boil"), from PIE root *wel- "to turn, roll" (see vulva), on notion of "roiling or bubbling water."