UMO can refer to: Unknown Mortal Orchestra, a psychedelic rock band from New Zealand United Macedonian Organisation: Ilinden–Pirin, a Macedonian organization in Bulgaria University of Maine at Orono (unofficial abbreviation) Mozilla Add-ons, a website formerly referred to as UMO (from update.mozilla.org) UMO Jazz Orchestra, a Finnish big band University of Mount Olive, a private Christian University located in Mount Olive, North Carolina, USA.