Words and Proper Names

laicus (L)

Sharpe (Richard): Hiberno-Latin laicus, Irish láech and the devil’s men.
In Ériu 30 (1979), pp. 75–92.
Lat. laicus ‘layman’ introduced to Irel. and developed the rare subsidiary meaning ‘lay tenant’ in ecclesiastical context; laicus develops pagan connotations, hence ‘brigand’. In a separate line of development, Lat. laicus ‘layman’ borrowed into Ir. as láech at an early date primarily in legal texts; láech ‘warrior’ may have developed on the principle that ‘men’ are ‘warriors’ (see P. Mac Cana, ‘On the word láech “warrior” ', in Celtica 11 (1976), pp. 125-128); láech ‘warrior’ in turn influences Lat. laicus, which acquires the rare meaning ‘warrior’; láech ‘pagan’ occurs as a calque on laicus ‘pagan’.
Mac Cana (Proinsias) (ref.)