Source : Webster's Revised Unabridged Dictionary (1913)

Excommunicate \Ex`com*mu"ni*cate\, v. t. [imp. & p. p.
   {Excommunicated}; p. pr. & vb. n. {Excommunicating}.]
   1. To put out of communion; especially, to cut off, or shut
      out, from communion with the church, by an ecclesiastical
      sentence.

   2. To lay under the ban of the church; to interdict.

            Martin the Fifth . . . was the first that
            excommunicated the reading of heretical books.
                                                  --Miltin.