epithalamium
noun
ep·i·tha·la·mi·um ˌe-pə-thə-ˈlā-mē-əm 
variants or epithalamion
ˌe-pə-thə-ˈlā-mē-ən
plural epithalamiums or epithalamia ˌe-pə-thə-ˈlā-mē-ə
: a song or poem in honor of a bride and bridegroom
epithalamic
ˌe-pə-thə-ˈla-mik
adjective 
Word History
Etymology
Latin & Greek; Latin epithalamium, from Greek epithalamion, from epi- + thalamos room, bridal chamber; perhaps akin to Greek tholos rotunda
First Known Use
1588, in the meaning defined above