early 15c., from Old French vexer "vex, harass" (14c.), from Latin vexare "to shake, jolt, toss violently;" figuratively "attack, harass, trouble, annoy," from vexus, collateral form of vectus, past participle of vehere "to draw, carry" (from PIE root *wegh- "to go, move, transport in a vehicle"). Related: Vexed; vexing.
Proto-Indo-European root meaning "to go, move, transport in a vehicle."
The root wegh-, "to convey, especially by wheeled vehicle," is found in virtually every branch of Indo-European, including now Anatolian. The root, as well as other widely represented roots such as aks- and nobh-, attests to the presence of the wheel — and vehicles using it — at the time Proto-Indo-European was spoken. [Watkins, p. 96]
It forms all or part of: always; away; convection; convey; convex; convoy; deviate; devious; envoy; evection; earwig; foy; graywacke; impervious; invective; inveigh; invoice; Norway; obviate; obvious; ochlocracy; ogee; pervious; previous; provection; quadrivium; thalweg; trivia; trivial; trivium; vector; vehemence; vehement; vehicle; vex; via; viaduct; viatic; viaticum; vogue; voyage; wacke; wag; waggish; wagon; wain; wall-eyed; wave (n.); way; wee; weigh; weight; wey; wiggle.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit vahati "carries, conveys," vahitram, vahanam "vessel, ship;" Avestan vazaiti "he leads, draws;" Greek okhos "carriage, chariot;" Latin vehere "to carry, convey," vehiculum "carriage, chariot;" Old Church Slavonic vesti "to carry, convey," vozŭ "carriage, chariot;" Russian povozka "small sled;" Lithuanian vežu, vežti "to carry, convey," važis "a small sled;" Old Irish fecht "campaign, journey," fen "carriage, cart;" Welsh gwain "carriage, cart;" Old English wegan "to carry;" Old Norse vegr, Old High German weg "way;" Middle Dutch wagen "wagon."
c. 1400, "to vex, irritate," probably a back-formation from crabbed. The notions of "bad-tempered, combative" and "sour" in the two nouns crab naturally yielded a verb meaning of "to vex, irritate," later "to complain irritably, find fault" (c. 1500). As "to fish for crabs" from 1650s (implied in crabbing). The noun meaning "sour person" is from 1570s.
late 15c. (Caxton), "infest with disease or other natural calamity," from Middle Dutch plaghen, from plaghe (n.) "plague" (see plague (n.)). The sense of "vex, harass, bother, annoy" is recorded from 1590s. Related: Plagued; plaguing.
late 14c., distemperen, "to disturb, upset the proper balance of," from Old French destemprer and directly from Medieval Latin distemperare "vex, make ill," literally "upset the proper balance (of bodily humors)," from dis- "un-, not" (see dis-) + Latin temperare "mingle in the proper proportion" (see temper (v.)). Related: Distempered.