It's the Italian for Orpheus, as in the musician from Greek myths. As well as being a reference to the subject of the first opera, it serves as an extremely obscure reference to one of my favourite Tori Amos songs.
Delmer because that's what my aunt Audrey named me in 1938. She was only 18 and dying of tuberculosis so my folks let her name their firstborn. Delmer was the name of a neighbor boy who was her boyfriend and pretty much stayed by her side constantly until she died.