Source : Webster's Revised Unabridged Dictionary (1913)

Subvene \Sub*vene"\, v. i. [imp. & p. p. {Subvened}; p. pr. &
   vb. n. {Subvening}.] [Pref. sub- + L. venire to come. See
   {Subvention}.]
   To come under, as a support or stay; to happen.

         A future state must needs subvene to prevent the whole
         edifice from falling into ruin.          --Bp.
                                                  Warburton.