[syn: irritating, painful]
The Collaborative International Dictionary of English v.0.48:
irritating \irritating\ adj.
   1. causing annoyance.
   Syn: annoying, galling, chafing, nettlesome, pesky,
        pestiferous, pestilent, plaguy, plaguey, teasing,
        vexatious, vexing.
        [WordNet 1.5 +PJC]
   2. causing irritation of living tissue; -- used of physical
      stimuli.
   Syn: irritant, irritative.
        [WordNet 1.5 +PJC]
   3. causing pain or physical discomfort; as, an irritating
      burr under his stocking.
   Syn: painful.
        [WordNet 1.5]
The Collaborative International Dictionary of English v.0.48:
Irritate \Ir"ri*tate\, v. t. [imp. & p. p. Irritated; p. pr. &
   vb. n. Irritating.] [L. irritatus, p. p. of irritare. Of
   doubtful origin.]
   [1913 Webster]
   1. To increase the action or violence of; to heighten
      excitement in; to intensify; to stimulate.
      [1913 Webster]
            Cold maketh the spirits vigorous and irritateth
            them.                                 --Bacon.
      [1913 Webster]
   2. To excite anger or displeasure in; to provoke; to tease;
      to exasperate; to annoy; to vex; as, the insolence of a
      tyrant irritates his subjects.
      [1913 Webster]
            Dismiss the man, nor irritate the god:
            Prevent the rage of him who reigns above. --Pope.
      [1913 Webster]
   3. (Physiol.) To produce irritation in; to stimulate; to
      cause to contract. See Irritation, n., 2.
      [1913 Webster]
   4. (Med.) To make morbidly excitable, or oversensitive; to
      fret; as, the skin is irritated by friction; to irritate a
      wound by a coarse bandage.
   Syn: To fret; inflame; excite; provoke; tease; vex;
        exasperate; anger; incense; enrage.
   Usage: To Irritate, Provoke, Exasperate. These words
          express different stages of excited or angry feeling.
          Irritate denotes an excitement of quick and slightly
          angry feeling which is only momentary; as, irritated
          by a hasty remark. To provoke implies the awakening of
          some open expression of decided anger; as, a provoking
          insult. Exasperate denotes a provoking of anger at
          something unendurable. Whatever comes across our
          feelings irritates; whatever excites anger provokes;
          whatever raises anger to a high point exasperates.
          "Susceptible and nervous people are most easily
          irritated; proud people are quickly provoked; hot and
          fiery people are soonest exasperated." --Crabb.
          [1913 Webster]
WordNet (r) 3.0 (2006):
irritating
    adj 1: causing irritation or annoyance; "tapping an annoying
           rhythm on his glass with his fork"; "aircraft noise is
           particularly bothersome near the airport"; "found it
           galling to have to ask permission"; "an irritating
           delay"; "nettlesome paperwork"; "a pesky mosquito";
           "swarms of pestering gnats"; "a plaguey newfangled safety
           catch"; "a teasing and persistent thought annoyed him";
           "a vexatious child"; "it is vexing to have to admit you
           are wrong" [syn: annoying, bothersome, galling,
           irritating, nettlesome, pesky, pestering,
           pestiferous, plaguy, plaguey, teasing,
           vexatious, vexing]
    2: (used of physical stimuli) serving to stimulate or excite;
       "an irritative agent" [syn: irritating, irritative]
    3: causing physical discomfort; "bites of black flies are more
       than irritating; they can be very painful" [syn:
       irritating, painful]
Moby Thesaurus II by Grady Ward, 1.0:
69 Moby Thesaurus words for "irritating":
   acerbic, acid, acrid, aggravating, aggravative, annoying, asperous,
   astringent, biting, bitter, bothering, bothersome, caustic,
   chafing, contentious, cutting, disturbing, escharotic,
   exasperating, exasperative, fretting, galling, grating, grinding,
   harassing, harsh, importunate, importune, irking, irksome,
   irritant, irritative, keen, mordant, nose-tickling, penetrating,
   pesky, pestering, pestiferous, pestilent, pestilential, piercing,
   piquant, plaguesome, plaguey, plaguing, poignant, provocative,
   provoking, pungent, rasping, rough, scratchy, severe, sharp, sour,
   stinging, teasing, tiresome, tormenting, trenchant, troublesome,
   troubling, vexatious, vexing, vitriolic, wearisome, worrisome,
   worrying