willyoudaoicibaDictYouDict[will 词源字典]
will: Will the noun [OE] and the two verbs will [OE] all go back ultimately to the Indo- European base *wel-, *wol- ‘be pleasing’, which also produced English voluntary, voluptuous, wealth, well ‘satisfactorily’, etc. From it was derived a noun, *weljon, which evolved into English will, and also German wille, Dutch wil, Swedish vilja, and Danish vilje.

The verb will ‘decide on or resolve by force of the will’ was formed in the prehistoric Germanic period from the noun. The auxiliary verb will, expressing intention or future time, comes from a prehistoric Germanic *weljan. Would evolved from its original Old English past form wolde.
=> voluntary, voluptuous, wealth, will, would[will etymology, will origin, 英语词源]
will (v.1)youdaoicibaDictYouDict
Old English *willan, wyllan "to wish, desire; be willing; be used to; be about to" (past tense wolde), from Proto-Germanic *willjan (cognates: Old Saxon willian, Old Norse vilja, Old Frisian willa, Dutch willen, Old High German wellan, German wollen, Gothic wiljan "to will, wish, desire," Gothic waljan "to choose").

The Germanic words are from PIE root *wel- (2) "to wish, will" (cognates: Sanskrit vrnoti "chooses, prefers," varyah "to be chosen, eligible, excellent," varanam "choosing;" Avestan verenav- "to wish, will, choose;" Greek elpis "hope;" Latin volo, velle "to wish, will, desire;" Old Church Slavonic voljo, voliti "to will," veljo, veleti "to command;" Lithuanian velyti "to wish, favor," pa-velmi "I will," viliuos "I hope;" Welsh gwell "better").

Compare also Old English wel "well," literally "according to one's wish;" wela "well-being, riches." The use as a future auxiliary was already developing in Old English. The implication of intention or volition distinguishes it from shall, which expresses or implies obligation or necessity. Contracted forms, especially after pronouns, began to appear 16c., as in sheele for "she will." The form with an apostrophe is from 17c.
will (n.)youdaoicibaDictYouDict
Old English will, willa "mind, determination, purpose; desire, wish, request; joy, delight," from Proto-Germanic *wiljon- (cognates: Old Saxon willio, Old Norse vili, Old Frisian willa, Dutch wil, Old High German willio, German Wille, Gothic wilja "will"), related to *willan "to wish" (see will (v.1)). The meaning "written document expressing a person's wishes about disposition of property after death" is first recorded late 14c.
will (v.2)youdaoicibaDictYouDict
Old English willian "to determine by act of choice," from will (n.). From mid-15c. as "dispose of by will or testament." Often difficult to distinguish from will (v.1).