List of Acronyms and Initialisms: O - ON

ON

• ON – (s) Ontario (postal symbol)
• Onna – Oniong, Nnung Ndem, and Awa, a Local Government Area in Nigeria
• ONC – (i) Orthopaedic Nurse Certified
• ONCE – (a) Organización Nacional de Ciegos Españoles (Spanish, "National Organization for the Spanish Blind")
• ONÉRA – (a) Office national d'études et de recherches aérospatiales (French, "Aeronautics and Space Research Center")
• ONG – (i) Orthodontic National Group
• ONH – (i) Óglaigh na hÉireann (Irish idiom for "soldiers of Ireland"), used for the following:
  • Historically, as the Irish-language name for the original Irish Republican Army ("Old IRA")
  • In modern times, as the Irish-language name of the Defence Forces of Ireland
  • The name of two groups claiming descent from the Old IRA, one a currently inactive splinter group of the Continuity IRA and the other an active splinter group of the Real IRA
• ONI – (i) (U.S.) Office of Naval Intelligence
• ONS – (i) Operational Needs Statement