What does On stand for?

Onorevole - Honorable - Italian (AD)

Onsdag - Wednesday - Danish (AD)

Octane Number (AD)

Omni Nocte - Every Night - Latin (AD)

Onomastikon - Lexicon - Greek (AD)

Onstage - Theater (WDMC)

Air Nauru - ICAO designator (AD)

Central Branch, Nepean Public Library, Ontario - Library symbol - National Library of Canada (NLC)

McKinley Memorial Library, Niles, OH - Library symbol - Library of Congress (LCLS)

Mortar launcher - NCIC gun type code (NCIC)

New Order - Revolutionary group - Italy

Obsessional Neurosis - Medicine (EDAA)

Obstructive Nephropathy - Medicine (MELL)

Occipitonuchal - Medicine (EDAA)

Occupational Nursing (SAUS)

Octane Number - Fuel terminology

Oculonasal - Anatomy

Office Note

Office Nurse

Officer's Name (NITA)

Official Number (DS)

Off Normal

Ogden Nash (AD)

Oil-Immersed Natural-Colled Transformer (IAA)

Oil-immersed Natural-cooled (or cooling) (SAUS)

Old Norse - Language, etc.

Olfactory Nerve - Neuroanatomy

Oligonucleotide - Chemistry

Omega Navigation (PDAA)

Omega Neuron - Neuroanatomy

Omni Nocte - Every Night - Pharmacy

Oncology - Medical specialty (DHSM)

Oncor - Tire retread brand

Onions (ROG)

Onorevole - Honorable (EY)

Ontario - Canadian province - Postal code

Ontario Northland Railway - Canada (AD)

OnX Enterprise Solutions - Toronto Stock Exchange symbol - Canada

Opera News - A publication (BRI)

Operation Notice (AAG)

Operation Number (ELAL)

Optic Nerve - Anatomy

Optic Neuritis (SAUS)

Optic Neuropathy (SAUS)

Order Number (NITA)

Ordre Nouveau - New Order - France - Political party (WDAA)

Oregon - Obsolete (ROG)

Original Negative (MCD)

Oronasal - Medicine (EDAA)

Ortho-Novum - A contraceptive - Ortho Pharmaceutical Corp. (DAVI)

Orthopedic Nurse

Osteonecrosis - Medicine (EDAA)

Other Networks (SAUS)

Our Neighbours - A publication

Overnighter (SAUS)

Oxidation Number (IAA)