Achill, Acaill (meaning uncertain). The name appears as Ecaill, Eccuill in various Irish sources, including A Conn, 1235, and Akill, Akle, The Aukilles, etc. in late-16th century English sources.
The name occurs eleswhere throughout Ireland, most notably as the ancient name of the Hill of Skreen in County Meath.
It has been suggested that the name may mean 'look-out, prospect'; the idea sometimes advanced that it may be related to the Latin word aquila, 'an egale', seems groundless.
Extract from: "MAYO - Aspects of its Heritage", by Bernard O'Hara. Published by kind permission of author