"Oa, a headland and a quoad sacra parish in Kildalton parish, Islay island, Argyllshire. The headIand, flanking the S side or Laggan Bay, 3½ miles NW or Port Ellen and 7½ S of Bowmore, overlooks the E side of the entrance of Loch Indal; has a beetling, lofty, imposing character; is crowned with the ruins or DUNAIDH Castle; was originally called Keannoath; is now called the Mull or Oa; and often gives its name of Oa to much or all of the entire south-eastern peninsula of Islay. The quoad sacra parish, which comprises the southern part of that peninsula, and which has for its post-town either Port Ellen or Bowmore, was constituted first by the ecclesiastical authorities, next in 1849 by the court of teinds. It is in the presbytery of Islay and Jura and the synod of Argyll; its minister's stipend is £160 with a manse. The church was built at the expense or government in the first half or the 19th century. Pop. (1871) 367, (1881) 247, (1891) 210, of whom 200 were Gaelic-speaking."
Extract from Groome's Ordnance Gazetteer of Scotland, 1896