Named my daughter this in 1990. She has grown to merit its beauty and dignity. Looked up the meaning in several old books at the time. Got these meanings: "fair of brow"-- or "white of brow". Also her father found "bright eyed elf" although I can't vouch for that one.
After having the name of "Elowyne" for over 50 years, I have come across many meanings. "Camp El-O-win" in the Sierra's, it was told that it was an Indian name meaning "Happy House". Also a Welsh name for boys, Elowyne (also, Elwyn-a form of Alwyn, meaning great white or blessed. Male version of Alwen). Also, my Grandmother's name-- her mother found it in a book-- which I later found on Amazon. It's not trendy, or Elfin, although sounding like names in movies, books, etc. It's pronounced, at least for me, as L-O-WIN, (the sound of the letters & "win", like you "win" a game). If you choose to bestow your daughter with this name, she would be very fortunate. It's a good name to have. ;)