The Collaborative International Dictionary of English v.0.48:

Vex \Vex\, v. i.
   To be irritated; to fret. [R.] --Chapman.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Vex \Vex\ (v[e^]ks), v. t. [imp. & p. p. Vexed (v[e^]kst); p.
   pr. & vb. n. Vexing.] [F. vexer, L. vexare, vexatum, to
   vex, originally, to shake, toss, in carrying, v. intens. fr.
   vehere, vectum, to carry. See Vehicle.]
   1. To toss back and forth; to agitate; to disquiet.
      [1913 Webster]

            White curl the waves, and the vexed ocean roars.
                                                  --Pope.
      [1913 Webster]

   2. To make angry or annoyed by little provocations; to
      irritate; to plague; to torment; to harass; to afflict; to
      trouble; to tease. "I will not vex your souls." --Shak.
      [1913 Webster]

            Ten thousand torments vex my heart.   --Prior.
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   3. To twist; to weave. [R.]
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            Some English wool, vexed in a Belgian loom.
                                                  --Dryden.
      [1913 Webster]

   Syn: See Tease.
        [1913 Webster]

WordNet (r) 3.0 (2006):

vex
    v 1: cause annoyance in; disturb, especially by minor
         irritations; "Mosquitoes buzzing in my ear really bothers
         me"; "It irritates me that she never closes the door after
         she leaves" [syn: annoy, rag, get to, bother, get
         at, irritate, rile, nark, nettle, gravel, vex,
         chafe, devil]
    2: disturb the peace of mind of; afflict with mental agitation
       or distress; "I cannot sleep--my daughter's health is
       worrying me" [syn: worry, vex] [ant: assure,
       reassure]
    3: change the arrangement or position of [syn: agitate, vex,
       disturb, commove, shake up, stir up, raise up]
    4: subject to prolonged examination, discussion, or
       deliberation; "vex the subject of the death penalty"
    5: be a mystery or bewildering to; "This beats me!"; "Got me--I
       don't know the answer!"; "a vexing problem"; "This question
       really stuck me" [syn: perplex, vex, stick, get,
       puzzle, mystify, baffle, beat, pose, bewilder,
       flummox, stupefy, nonplus, gravel, amaze,
       dumbfound]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "vex":
   abrade, aggravate, ail, anger, annoy, arouse, badger, bait, be at,
   be the matter, bedevil, beset, bother, bristle, brown off, bug,
   bullyrag, burn up, chafe, chaw, chivy, complicate matters, concern,
   devil, discommode, discompose, distemper, distress, disturb, dog,
   embarrass, embitter, exasperate, exercise, fash, fret, gall, get,
   gripe, harass, harry, haunt, heckle, hector, hound, huff, incense,
   inconvenience, inflame, infuriate, irk, irritate, miff, molest,
   nag, needle, nettle, nudzh, peeve, perplex, persecute, perturb,
   pester, pick on, pique, plague, pluck the beard, pother, provoke,
   put out, put to it, puzzle, rankle, ride, rile, roil, ruffle,
   set up, stir the blood, stir up, tease, torment, trouble,
   try the patience, tweak the nose, work up, worry