As or AS may stand for:

• A conjunction or preposition in the English language with various meanings.
• Advanced Subsidiary - A-levels
• Adult Swim, a comedy television block on the Cartoon Network.
• American Samoa, ISO 3166-1 country code
• Aortic stenosis
• arsenic (As), chemical symbol for the chemical element
• As in mythology:
  • in Norse mythology refers to the Aesir.
  • in Egyptian mythology is an alternate spelling for Ash (god).
• As (municipality) in Belgium
• As (coin) in Ancient Rome valued at 1/16 of a denarius
• Asperger's syndrome
• AS is the US Navy hull classification symbol for Submarine Tender
• Ankylosing spondylitis
• as in Unix is the standard command line assembler.
• The AS, a small French car.
• Assamese language (ISO 639 alpha-2)
• Autonomous system (Internet)
• Aš is a town in Czech Republic
• the IATA code for Alaska Airlines

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