1. 
[syn: distressing, distressful, disturbing, perturbing, troubling, worrisome, worrying]
The Collaborative International Dictionary of English v.0.48:
Trouble \Trou"ble\, v. t. [imp. & p. p. Troubled; p. pr. & vb.
   n. Troubling.] [F. troubler, OF. trobler, trubler,
   tourbler,fr. (assumed) LL. turbulare, L. turbare to
   disorderly group, a little crowd; both from turba a disorder,
   tumult, crowd; akin to Gr. ?, and perhaps to E. thorp; cf.
   Skr. tvar, tur,o hasten. Cf. Turbid.]
   1. To put into confused motion; to disturb; to agitate.
      [1913 Webster]
            An angel went down at a certain season into the
            pool, and troubled the water.         --John v. 4.
      [1913 Webster]
            God looking forth will trouble all his host.
                                                  --Milton.
      [1913 Webster]
   2. To disturb; to perplex; to afflict; to distress; to
      grieve; to fret; to annoy; to vex.
      [1913 Webster]
            Now is my soul troubled.              --John xii.
                                                  27.
      [1913 Webster]
            Take the boy to you; he so troubles me
            'T is past enduring.                  --Shak.
      [1913 Webster]
            Never trouble yourself about those faults which age
            will cure.                            --Locke.
      [1913 Webster]
   3. To give occasion for labor to; -- used in polite
      phraseology; as, I will not trouble you to deliver the
      letter.
      [1913 Webster]
   Syn: To disturb; perplex; afflict; distress; grieve; harass;
        annoy; tease; vex; molest.
        [1913 Webster]
WordNet (r) 3.0 (2006):
troubling
    adj 1: causing distress or worry or anxiety; "distressing (or
           disturbing) news"; "lived in heroic if something
           distressful isolation"; "a disturbing amount of crime";
           "a revelation that was most perturbing"; "a new and
           troubling thought"; "in a particularly worrisome
           predicament"; "a worrying situation"; "a worrying time"
           [syn: distressing, distressful, disturbing,
           perturbing, troubling, worrisome, worrying]
Moby Thesaurus II by Grady Ward, 1.0:
76 Moby Thesaurus words for "troubling":
   aggravating, agitating, annoying, bothering, bothersome,
   breathtaking, charged, cliff-hanging, disquieting, distracting,
   disturbing, electric, exasperating, exciting, exhilarating,
   galling, galvanic, harassing, heady, heart-expanding,
   heart-stirring, heart-swelling, heart-thrilling, importunate,
   importune, impressive, inflammatory, intoxicating, irking, irksome,
   irritating, jarring, jolting, maddening, mind-blowing, moving,
   overcoming, overmastering, overpowering, overwhelming, perturbing,
   pesky, pestering, pestiferous, pestilent, pestilential, piquant,
   plaguesome, plaguey, plaguing, provocative, provoking, ravishing,
   soul-stirring, spirit-stirring, stimulating, stimulative, stirring,
   striking, suspenseful, suspensive, tantalizing, teasing, telling,
   thrilling, thrilly, tiresome, tormenting, troublesome, unsettling,
   upsetting, vexatious, vexing, wearisome, worrisome, worrying