The Collaborative International Dictionary of English v.0.48:

Tiresome \Tire"some\, a.
   Fitted or tending to tire; exhausted; wearisome; fatiguing;
   tedious; as, a tiresome journey; a tiresome discourse. --
   Tire"some*ly, adv. -- Tire"some*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tiresome
    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:

88 Moby Thesaurus words for "tiresome":
   aggravating, annoying, bland, boresome, boring, bothering,
   bothersome, burdensome, common, commonplace, difficult,
   disagreeable, disturbing, draining, drudging, dull, exasperating,
   exhausting, fatiguesome, fatiguing, flat, galling, grueling,
   harassing, hard, humdrum, hypnotic, importunate, importune,
   insipid, irking, irksome, irritating, jading, killing,
   matter-of-fact, monotonous, mundane, onerous, oppressive, ordinary,
   pedestrian, pesky, pestering, pestiferous, pestilent, pestilential,
   plaguesome, plaguey, plaguing, plain, poetryless, prosaic, prosing,
   prosy, provoking, punishing, soporific, straining, stressful,
   stupefyingly boring, stuporific, teasing, tedious, tiring,
   toilsome, tormenting, troublesome, troubling, trying,
   unembellished, unidealistic, unimaginative, unimpassioned,
   uninteresting, unpleasant, unpoetic, unromantic, vapid, vexatious,
   vexing, weariful, wearing, wearisome, wearying, worrisome,
   worrying, yawny