Irish, from the deity name Lugh"light"
Luiseach Origin and Meaning
The name Luiseach is a girl's name of Irish Gaelic origin.
Authentically spelled Luíseach (with Luighsech as a variant), this obscure saint's name is thought to derive from the mythological figure Lugh, perhaps a reflex of an older god. Luíseach is sometimes considered the Irish version of Lucy. In fact, they are historically separate names, but if Lugh derives from a Proto-Indo-European root meaning "shining" then they are very distant cousins.