Bythwyn (m), Bythwen (f): A Fae species (Fata somnis) originating in the Neverworld, which feed upon the psychic energy of dreams. Bythwyn commonly exhibit telepathic and empathic abilities, among other powers, and may be aligned with any of the Fae Courts. The name “bythwyn” derives from the Brythonic Welsh language (“byth” = “never”, “wyn” or “wen” = “fair, blessed, pure, holy”) and/or possibly from the Middle or Early Modern English language (“bythwen” = “between”).
Neverworld (also, “Neverwhen” or “N’erewhon”): A dimension between, where all dreams, and nightmares, are possible. Strong emotions in dreams can often cause one to cross dimensions into the Neverworld during sleep, or in the transitional state between sleep and waking.
Nevereven (also “Ne’ere’en”) and Neverever (also, “Ne’ere’er”): Two of the known named realms of the Neverworld.
Neveryl: A colloquial name for the Bythwyn.
Neverling: A colloquial name for the changelings or halflings of the Bythwyn. May be considered insulting when applied to the Bythwyn themselves.
—from “Notes on the Origins of the Fae”, by Lady Míriel Emwy Seren Ferchrys (writing as “Meriel Whitford-Price”)