Source : Webster's Revised Unabridged Dictionary (1913)

Begnaw \Be*gnaw"\, v. t. [p. p. {Begnawed}, (R.) {Begnawn}.]
   [AS. begnagan; pref. be- + gnagan to gnaw.]
   To gnaw; to eat away; to corrode.

         The worm of conscience still begnaw thy soul. --Shak.