ONT

ONT may refer to:

• Ontario International Airport (IATA code ONT), in Ontario, California, United States
• Ontario (Ont.), traditional abbreviation for the Canadian province of Ontario; although ON is the proper postal abbreviation
• Optical Network Terminal, an interface between a company's fiber optic network and premises wiring
• Ontario Northland Railway, a Canadian railroad
• Ordo Novi Templi, Order of the New Templars, an occult anti-semitic society founded 1907 by Lanz von Liebenfels
• Ontario Network Television, the main predecessor of the now-defunct Baton Broadcast System (Canada)
• Obshchenatsional'noe Televidenie, a Belarusian national television station
• ortho-nitrotoluene, a type of mononitrotoluene, a nitro compound derivate of toluene
• Organización Nacional de Transplantes (Spanish Transplant Organization), which manages human organ and tissue transplants in Spain