NOS

NOS may refer to:

Science and technology

 * Nitrous oxide, also known as nos or laughing gas
 * 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

 * National Occupational Standards, UK
 * National Orange Show, San Bernardino, California, US
 * New Old Stock, unused old merchandise
 * NOS (drink), 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)