(no longer productive) Denotes the past participle form when attached to a verb. · (archaic) Denotes a quasi-past participle or participle-like adjective when attached to a noun or verb.
From Middle English sustren, plural of suster influenced by Old Norse systirin, plural of systir; the Old English plurals (of sweostor) were ġesweostor, ġesweostra, and ġesweostru. Analysable as sister + -en (plural ending).