NOS may refer to:
Science and technology Nitrous oxide, also known as nos Nitric oxide synthase, a class of enzymes Nitrous oxide system, an internal combustion engine Not Otherwise Specified, a categorization of illnesses Network operating system, a type of software NOS (operating system), a CDC network operating system KA9Q NOS, a TCP/IP implementation NOS stereo technique, for audio recording
Businesses and organizations National Ocean Service, US National Office of Statistics, Algeria National Orthodox School, Amman, Jordan Nederlandse Omroep Stichting, a Dutch public broadcasting corporation New Orleans Saints, an American football team Nitrous Oxide Systems, a subdivision of Holley Performance Products, an American automotive company NOS (Portuguese company) NOS, the ICAO designator of the now-defunct Norwegian airline, Norway Airlines NOS, the ICAO designator of the Italian airline Neos
Music Nos, an opera by Shostakovich N.O.S, part of the French rap duo PNL
Other uses Nation of Sanctuary, Welsh Government initiative National Occupational Standards, UK National Orange Show, San Bernardino, California, US New old stock, unused old merchandise NOS (drink), an energy drink from Monster Beverage Corporation, named after Nitrous Oxide Systems Nos: Book of the Resurrection, a book by Miguel Serrano Nos. or nos., the numero sign, an abbreviation of "numbers" Fascene Airport, Nosy Be, Madagascar (IATA code)
See also Nós Noss (disambiguation)