On

On, on, or ON may refer to:

On (Japanese prosody), the counting of sound units in Japanese poetry
Ön, a 1966 Swedish film
On (novel), by Adam Roberts
Air Nauru IATA airline designator ON
Heliopolis (ancient), an ancient city in Egypt, from a transliteration of its ancient Egyptian name
ITV Digital, a failed British digital television service originally named ONdigital
Leg side, in the game of cricket
Nintendo On, a fake video game console
Old Norse, a North Germanic language commonly referenced in etymology
Old Nottinghamian, a person who attended or worked at Nottingham High School
ON Semiconductor, a leading supplier of power management solutions
O'Nan group, a mathematical group
Ontario, Canada
Ontology, a branch of philosophy that deals with the concept of being
On'yomi reading of Japanese kanji characters
Osteonectin, a glycoprotein
Osteonecrosis
Order of the Nation, a Jamaican honour
Overground Network, a railway scheme in South London
Overmyer Network, an ill-fated US television network
OS/Net, the OpenSolaris Community
Optic_neuritis, especially relevant in multiple sclerosis

In popular music