late 14c., auctorisen, autorisen, "give formal approval or sanction to," also "confirm as authentic or true; regard (a book) as correct or trustworthy," from Old French autoriser, auctoriser "authorize, give authority to" (12c.) and directly from Medieval Latin auctorizare, from auctor (see author (n.)). Meaning "give authority or legal power to" is from mid-15c. Modern spelling from late 16c. Related: Authorized; authorizing. Authorized Version as a popular name for the 1611 ("King James") English Bible is by 1811.
Proto-Indo-European root meaning "to increase." It forms all or part of: auction; augment; augmentative; augur; August; august; Augustus; author; authoritarian; authorize; auxiliary; auxin; eke (v.); inaugurate; nickname; waist; wax (v.1) "grow bigger or greater."
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit ojas- "strength," vaksayati "cause to grow;" Lithuanian augu, augti "to grow," aukštas "high, of superior rank;" Greek auxo "increase," auxein "to increase;" Gothic aukan "to grow, increase;" Latin augmentum "an increase, growth," augere "to increase, make big, enlarge, enrich;" Old English eacien "to increase," German wachsen, Gothic wahsjan "to grow, increase."
1660s, "empower or authorize by commission," from commission (n.). In the naval sense, of persons, "be given the rank of an officer (by commission from authority)," from 1793; of a ship, "to be transferred from the naval yard and placed in the command of the officer put in charge of it," 1796. Related: Commissioned; commissioning.
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" (source also of Old High German werento "guarantor," noun use of present participle of weren "to authorize, warrant;" German gewähren "to grant"), from PIE root *wer- (4) "to cover."
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).