The story
- Proto-Germanic · inherited from*underkuningaz
- Proto-West Germanic · inherited from*underkuning
- Old English · inherited fromundercing
- Middle English · inherited fromunderking
- English todayunderking
From Middle English underking, from Old English undercing, undercyning (“under-king, viceroy”), possibly from Proto-West Germanic *underkuning, from Proto-Germanic *underkuningaz, equivalent to under- + king. Cognate with Dutch onderkoning (“viceroy”), German Unterkönig (“underking”), Danish underkonge (“underking”), Swedish underkung (“underking”).
Etymology from Wiktionary, CC BY-SA 4.0.