... The island of Avalon may have been named after Avalloc, (Avallach), who lived there with his daughters.  He is also called Rex Avallon.  It was to his palace that Arthur was brought and healed by the regia virgo (San Marte, 425).  He may therefore have been a mythical lord of the Other-world, a king of the dead, and his daughters would correspond to the maidens of the isle... (Encyclopaedia of Religion and Ethics, v.2, 1910)

    Mr. Whitaker says, "The principal production of our orchards has derived its present appellation among us from the British language; and in the Welsh, Armorican, and Irish is invariably denominated the avall, aball, or apple: and it seems to have been brought into Britain by the first colonies of the natives, and by the haedui of Somersetshire particularly.  Hence we find the present scite of Glastonbury to have been distinguished before the arrival of the Romans by the significant title of Avallonia, or the Apple Orchard.  The fruit also so strongly recommended itself to the British, that another Avellena arose in the North of England."
    "The spot, says the historian of Somerset, was at this early period called by the natives Inswytryn, or the Glassy Island, either because its surface represented glasten, or blue green colour; or because it abounded with the herb glast or woad, with which they were used to tinge their bodies.  In after times it received the fancied name of Avallon, or the Isle of Apples; or the land where Avalloc, a British chief, first pitched his residence: the Saxons finally calling it Glaestingabyrig."
    To these authorities I must add that Iniswitrin comes from the Gaelic word Inis an island; wit an hill; and rinn, a ridge, point, or peak; and these terms very appropriately imply the peak hill island.
    I beg also to state that if Avalon be derived from aval an apple, and on be an augment, then this name will imply the GREAT APPLE! (A Restoration of the Ancient Modes of Bestowing Names on the Rivers, Hills, &c., Dyer, 1805)