Source : Webster's Revised Unabridged Dictionary (1913)

Epithalamium \Ep`i*tha*la"mi*um\, n.; pl. {Epithalamiums}, L.
   {Epithalamia}. [L., fr. Gr. ?, orig. an adj., nuptial; 'epi`
   upon, at + ? bride chamber.]
   A nuptial song, or poem in honor of the bride and bridegroom.

         The kind of poem which was called epithalamium . . .
         sung when the bride was led into her chamber. --B.
                                                  Jonson.