The Collaborative International Dictionary of English v.0.48:

Xenium \Xe"ni*um\ (z[=e]"n[i^]*[u^]m), n.; pl. Xenia
   (z[=e]"n[i^]*[.a]). [L., from Gr. xe`nion gift to a guest,
   fr. xe`nos guest.] (Class. Antiq.)
   A present given to a guest or stranger, or to a foreign
   ambassador.
   [1913 Webster]