Source : Webster's Revised Unabridged Dictionary (1913)

Invoke \In*voke"\, v. t. [imp. & p. p. {Invoked}; p. pr. & vb.
   n. {Invoking}.] [F. invoquer, L. invocare; pref. in- in, on +
   vocare to call, fr. vox voice. See {Voice}, and cf.
   {Invocate}.]
   To call on for aid or protection; to invite earnestly or
   solemnly; to summon; to address in prayer; to solicit or
   demand by invocation; to implore; as, to invoke the Supreme
   Being, or to invoke His and blessing.

         Go, my dread lord, to your great grandsire's tomb, . .
         . Invoke his warlike spirit.             --Shak.