A Aindriú a chara / Hi Andrew, I don't know whether this will help, but moen / moan is an Irish word meaning 'silent' / 'dumb' / 'mute'.  It's a mythological reference to Labraid Moen, the primary ancestor-hero or ancestor-god of the Laighin who once held not only Leinster but Fir nÓl nÉcmacht, i.e., Connacht before it was conquered by the Connachta. There's a plain there called Magh Moen (Plain of the Silent One), also known as Moenmagh.  It's the plain around Loughrea in Co. Galway.  I wondered whether that powerful tradition might have influenced someone to take Moan / Moen as a surname in that area. So, on a hunch, I browsed for "co. galway moan surname" and found this: http://www.surnamedb.com/Surname/Moen Don't know if it's helpful but go n-éirí an t-ádh leat ar do sheilg / good luck on your search. Le gach dea-ghuí / Best, Jerry Treibheanna Éireannacha www.irishtribes.com