Source : Webster's Revised Unabridged Dictionary (1913)

Agonize \Ag"o*nize\, v. i. [imp. & p. p. {Agonized}; p. pr. &
   vb. n. {Agonizing}.] [F. agoniser, LL. agonizare, fr. Gr. ?.
   See {Agony}.]
   1. To writhe with agony; to suffer violent anguish.

            To smart and agonize at every pore.   --Pope.

   2. To struggle; to wrestle; to strive desperately.

Agonize \Ag"o*nize\, v. t.
   To cause to suffer agony; to subject to extreme pain; to
   torture.

         He agonized his mother by his behavior.  --Thackeray.

Source : WordNet®

agonize
     v 1: cause to agonize [syn: {agonise}]
     2: suffer agony or anguish [syn: {agonise}]