Well, the word 'wing' does date back to the 12th century, a little earlier than halfway between us and Merlin, and a time in which learned people did know Latin but were also starting to mangle it up pretty badly (not quite that badly IRL, but if we assume wizards were always a bit more eccentric than Muggles...).

Unfortunately, that particular fan-wank completely breaks down when you consider that the pronunciation (let alone spelling) of 'wing' was nowhere near the same back then. Although you could save it by suggesting that, just as spoken language evolves really, really slowly, so did the spell-marks imprinted on reality as the spell got cast a million times over a thousand years, a wee little bit differently every time.