What is "rinnal"

In Irish mythology, Rinnal (Rindal, Rionnal, Rinnan) son of Genann of the Fir Bolg became High King of Ireland when he overthrew Fiacha Cennfinnán. He is said to have been the first king in Ireland to use spearheads (cf. Old Irish rind, rinn, (spear-)point).

He ruled for five or six years (depending on the source) before being overthrown by his cousin Fodbgen, son of Sengann.