eftir

Apparently orphan is from PIE *orbho- "bereft of father," or, interestingly, "deprived of free status." In fact that makes sense in the context of archaic heroic society. By definition, slaves have no kin; kinless folk are like slaves, like the unfree, because they have no fathers, uncles, brothers to act on their behalf, bring legal suits, avenge their deaths.

Heartening, maybe, but also sad is the relationship to Ger erbe, OIr orbe, OE, ierfa, ON arfr, erfð, erfðingi, all to do with heirs and inheritance. Or merely OE earfoð, hardship. (Further on, Germ arbeit, but that goes without saying.)

The base is *orbh-, having to do with changes in status and allegiance. I think of fardagar, moving days, when it was permitted to cut ties with one farm and attach yourself to another. Longer ago, when it was permitted to shift official loyalty from one goði to another. The orphan would seem to be the one who unhitches (or is unhitched) from one fast point only to feel himself swinging suddenly, horribly, free ---there is nothing for him to bind himself to anew.