The Collaborative International Dictionary of English v.0.48:

Nunciature \Nun"ci*a*ture\, n. [L. nunciare, nuntiare, to
   announce, report, fr. nuncius, nuntius, messenger: cf. F.
   nonciature, It. nunziatura. See Nuncio.]
   The office of a nuncio. --Clarendon.
   [1913 Webster]