The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
wel-1
DEFINITION:
To wish, will. Derivatives include wealth, gallop, gallant, and voluptuous. 1.well2, from Old English wel, well (< “according to one's wish”), from Germanic *wel-.2.weal1, wealth, from Old English wela,weola, well-being, riches, from Germanic *weln-.3.will1, from Old English willa, desire, will power, from Germanic *wiljn-.4.will2; nill, willy-nilly, from Old English willan, to desire, from Germanic *wil(l)jan.5. Germanic compound *wil-kumn- (see gw-). 6. O-grade form *wol-.a.gallop, from Old French galoper, to gallop; b.wallop, from Old North French *waloper, to gallop; c.gallant; gallimaufry, from Old French galer, to rejoice, from Frankish Latin *walre, to take it easy, from Frankish *wala, good, well. a–c all from Germanic *wal-.7. Basic form *wel-.velleity, volition, voluntary; benevolent, malevolence, from Latin velle (present stem vol-), to wish, will. 8. Probably suffixed extended form *wel-p-i-.voluptuary, voluptuous, from Latin volupts, pleasure, from an adjective *volupis, pleasing (probably preserved in the adverb volup, with pleasure, from neuter *volupe). (Pokorny 2. el- 1137.)
n-. 3. will1, from Old English willa, desire, will power, from Germanic *wilj
-). 6. O-grade form *wol-. a. gallop, from Old French galoper, to gallop; b. wallop, from Old North French *waloper, to gallop; c. gallant; gallimaufry, from Old French galer, to rejoice, from Frankish Latin *wal
el- 1137.) 
