An Etymological Dictionary of the German Language/Dirne
Dirne, f., ‘lass, hussy, wench’ (not found in UpG.), from MidHG. dirne, dierne, OHG. diorna, ‘maid-servant, girl, wench,’ Comp. Du. deern, OSax. thiorna, OIc. þerna, f.; in Goth. probably *þiwaírnô; comp. widuwaírna, ‘orphan,’ orig. sense perhaps ‘widow's son.’ Thus, too, *þiwaírnô, ‘menial's, thrall's daughter, who is therefore herself a slave, i.e, a servant.’ The deriv. syllable is a diminutive suffix (comp. Eichhorn); the stem is indisputably þiwa-, ‘menial.’ For further cognates, see dienen, Degen.