An Etymological Dictionary of the German Language/Annotated/Dirne
Dirne, feminine, ‘lass, hussy, wench’ (not found in Upper German), from Middle High German dirne, dierne, Old High German diorna, ‘maid-servant, girl, wench,’ Compare Dutch deern, Old Saxon thiorna, Old Icelandic þerna, feminine; in Gothic probably *þiwaírnô; compare widuwaírna, ‘orphan,’ original sense perhaps ‘widow's son.’ Thus, too, *þiwaírnô, ‘menial's, thrall's daughter, who is therefore herself a slave, i.e, a servant.’ The derivative syllable is a diminutive suffix (compare Eichhorn); the stem is indisputably þiwa-, ‘menial.’ For further cognates, see dienen, Degen.