S. erin ? “on the ... day”
Carl Hostetter suggested (VT31/26) that this form is some derivative of the root ᴹ√AR¹ “day” while David Salo suggested it is a prepositional form combining (N.) or “above” with the definite article, perhaps with the sense “[up]on the”. Neither explanation seems especially compelling, but I can’t think of a better one.
References ✧ SD/129