Sources

“[aç’losən]. 1488, Auchinlossin A2. Stressed on second syllable, which has a close o, rather long. M[acDonald] says there was an old tale of a giant frog (losgann) which once lived in the Loch of Auchlossan; hence Ach an losgainn, field of the frog. He also offers Ach an liosain, field of the little fort or garden; which does not fit the stressed o.” Alexander 154-5

Ach-lōsin Diack MS2276