warrantyoudaoicibaDictYouDict[warrant 词源字典]
warrant: [13] Warrant probably goes back ultimately to werenti ‘protector’, a noun use of the present participle of Old High German werren ‘protect’, which in turn was formed from the base *wer- ‘watch, be on one’s guard, take care’ (source of English ward, wary, etc). This was borrowed into medieval Latin as warantus, and passed into English via Old Northern French warant. The central Old French form of the word was garant, which passed into English via Spanish as guarantee.
=> guarantee, ware[warrant etymology, warrant origin, 英语词源]
warrant (n.)youdaoicibaDictYouDict
c. 1200, "protector, defender," from Old North French warant "defender; surety, pledge; justifying evidence" (Old French garant), from Frankish *warand, from Proto-Germanic *war- "to warn, guard, protect" (cognates: Old High German werento "guarantor," noun use of present participle of weren "to authorize, warrant;" German gewähren "to grant"), from PIE root *wer- (5) "to cover" (see weir).

Sense evolved via notion of "permission from a superior which protects one from blame or responsibility" (early 14c.) to "document conveying authority" (1510s). A warrant officer in the military is one who holds office by warrant (as from a government department), rather than by commission (from a head of state).
warrant (v.)youdaoicibaDictYouDict
late 13c., "to keep safe from danger," from Old North French warantir "safeguard, protect; guarantee, pledge" (Old French garantir), from warant (see warrant (n.)). Meaning "to guarantee to be of quality" is attested from late 14c.; sense of "to guarantee as true" is recorded from c. 1300. Related: Warranted; warranting; warrantable.