Ringfort, enclosure. Written Lis, Liss — the same Irish word, lios, in the spellings English gave it.
Lios is a ringfort: the circular earthen bank and ditch inside which an early medieval farming family lived, of which some forty thousand survive as 'fairy forts' in fields across Ireland. A Lis- name (Lisdoonvarna, Lismore) marks one, usually with a description of it. Because the forts were left alone for fear of the fairies, the name often outlived any memory of the people who built it.
Source: P. W. Joyce, The Origin and History of Irish Names of Places (1869–1913) · Logainm ↗
Ringfort, enclosure: it is the Irish lios. Lios is a ringfort: the circular earthen bank and ditch inside which an early medieval farming family lived, of which some forty thousand survive as 'fairy forts' in fields across Ireland. A Lis- name (Lisdoonvarna, Lismore) marks one, usually with a description of it.
lios. English spellings of the same word include Lis, Liss, because the names were written down by ear.
Lisburn (Lios na gCearrbhach), Lisnaskea (Lios na Scéithe).