Source : Webster's Revised Unabridged Dictionary (1913)

Monstrance \Mon"strance\, n. [LL. monstrantia, fr. L. monstrare
   to show: cf. OF. monstrance. See {Monster}.] (R. C. Ch.)
   A transparent pyx, in which the consecrated host is exposed
   to view.

Source : WordNet®

monstrance
     n 1: proof by a process of argument or a series of proposition
          proving an asserted conclusion [syn: {demonstration}]
     2: (Roman Catholic Church) a vessel (usually of gold or silver)
        in which the consecrated Host is exposed for adoration