NOS

NOS may refer to:

Businesses and organisations

National Ocean Service, an office of the US government
National Office of Statistics, Algeria
National Open School (National Institute of Open Schooling), Board of Education for open schools in India
National Orthodox School, a private school in Amman, Jordan
De Nederlandse Omroep Stichting, Dutch public radio and television
Neotropical Ornithological Society
Nitrous Oxide Systems, a manufacturer of nitrous systems for high-performance automobiles
NOS (Portuguese media company), a media and telecommunications company

Network operating system, a kind of computer software for running local area networks
Nitrous oxide, N2O, a gas commonly referred to as "nitrous" or "NOS" in vehicle racing
Nitric oxide synthase, a class of enzymes
NOS (software), a primary operating system for a line of mainframe computers
NOS stereo technique, a method of capturing stereo sound
Not Otherwise Specified, a categorization of illnesses

National Occupational Standards, UK standards of work performance
New old stock, for sale merchandise manufactured long ago but never yet used
NOS (drink), a beverage named after Nitrous Oxide Systems
Nos, Book of the Resurrection (Nos: Libro de la Resurrección), a book by Miguel Serrano
Nos. or nos., also called the Numero sign, an abbreviation of the word "Numbers"