Source : Webster's Revised Unabridged Dictionary (1913)

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.

            An angel went down at a certain season into the
            pool, and troubled the water.         --John v. 4.

            God looking forth will trouble all his host.
                                                  --Milton.

   2. To disturb; to perplex; to afflict; to distress; to
      grieve; to fret; to annoy; to vex.

            Now is my soul troubled.              --John xii.
                                                  27.

            Take the boy to you; he so troubles me 'T is past
            enduring.                             --Shak.

            Never trouble yourself about those faults which age
            will cure.                            --Locke.

   3. To give occasion for labor to; -- used in polite
      phraseology; as, I will not trouble you to deliver the
      letter.

   Syn: To disturb; perplex; afflict; distress; grieve; harass;
        annoy; tease; vex; molest.

Source : WordNet®

troubling
     adj : 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},
            {worrisome}, {worrying}]