prothalamium
/ˌprəʊθəˈleɪmɪəm
/noun (plural prothalamia /ˌprəʊθəˈleɪmɪə/) literary
A song or poem celebrating a forthcoming wedding.John Ashbery, in ‘A Blessing in Disguise,’ has written a fast, sure prothalamion for the sometime wedding of oneself to the free friend, to poetry.
Origin
Late 16th century: from Prothalamion, the title of a poem by Spenser, on the pattern of epithalamium.