Compare Marathi -ऊन (-ūn). This etymology is incomplete. You can help Wiktionary by elaborating on the origins of this term.
-ਓਂ • (-õ)[1]
- from, though
- ^ Singh, Bhai Maya (1895) “ਓਂ”, in The Panjabi Dictionary, Lahore: Munshi Gulab Singh and Sons, page 833.