1. 
[syn: boring, deadening, dull, ho-hum, irksome, slow, tedious, tiresome, wearisome]
The Collaborative International Dictionary of English v.0.48:
Irksome \Irk"some\, a.
   1. Wearisome; tedious; disagreeable or troublesome by reason
      of long continuance or repetition; as, irksome hours;
      irksome tasks.
      [1913 Webster]
            For not to irksome toil, but to delight,
            He made us.                           --Milton.
      [1913 Webster]
   2. Weary; vexed; uneasy. [Obs.]
      [1913 Webster]
            Let us therefore learn not to be irksome when God
            layeth his cross upon us.             --Latimer.
   Syn: Wearisome; tedious; tiresome; vexatious; burdensome.
   Usage: Irksome, Wearisome, Tedious. These epithets
          describe things which give pain or disgust. Irksome is
          applied to something which disgusts by its nature or
          quality; as, an irksome task. Wearisome denotes that
          which wearies or wears us out by severe labor; as,
          wearisome employment. Tedious is applied to something
          which tires us out by the length of time occupied in
          its performance; as, a tedious speech.
          [1913 Webster]
                Wearisome nights are appointed to me. --Job vii.
                                                  3.
          [1913 Webster]
                Pity only on fresh objects stays,
                But with the tedious sight of woes decays.
                                                  --Dryden.
          -- Irk"some*ly, adv. -- Irk"some*ness, n.
          [1913 Webster]
WordNet (r) 3.0 (2006):
irksome
    adj 1: so lacking in interest as to cause mental weariness; "a
           boring evening with uninteresting people"; "the deadening
           effect of some routine tasks"; "a dull play"; "his
           competent but dull performance"; "a ho-hum speaker who
           couldn't capture their attention"; "what an irksome task
           the writing of long letters is"- Edmund Burke; "tedious
           days on the train"; "the tiresome chirping of a cricket"-
           Mark Twain; "other people's dreams are dreadfully
           wearisome" [syn: boring, deadening, dull, ho-hum,
           irksome, slow, tedious, tiresome, wearisome]
Moby Thesaurus II by Grady Ward, 1.0:
61 Moby Thesaurus words for "irksome":
   aggravating, annoying, backbreaking, besetting, boresome, boring,
   bothering, bothersome, burdensome, chafing, crushing, disturbing,
   drudging, dull, exasperating, exhausting, fagging, fatiguing,
   galling, grueling, harassing, heavy, hefty, importunate, importune,
   irking, irritating, nettling, onerous, oppressive, painful, pesky,
   pestering, pestiferous, pestilent, pestilential, plaguesome,
   plaguey, plaguing, provoking, stupefyingly boring, stupid,
   stuporific, teasing, tedious, tiresome, tiring, tormenting,
   troublesome, troubling, trying, uninteresting, vexatious, vexing,
   weariful, wearing, wearisome, wearying, worrisome, worrying,
   yawny