"Also I now deeply regret having used Elves, though this is a word in ancestry and original meaning suitable enough. But the disastrous debasement of this word, in which Shakespeare played an unforgivable part, has really overloaded it with regrettable tones, which are too much to overcome."
JRRT - Letters #151, September 1954

"Elves has been used to translate both Quendi 'the speakers', the High-elven name of all their kind, and Eldar, the name of the Three Kindreds that sought for the Undying Realm... This old word was indeed the only one available, and was once fitted to apply to such memories of this people as Men preserved... But it has been diminished, and to many it may now suggest fancies either pretty or silly, as unlike to the Quendi of old as are butterflies to the swift falcon..."
RotK, Appendix F II - On Translation circa 1955