Na

NA, N.A., Na, nA or n/a may refer to:

Chemistry and physics

 * Sodium, symbol Na, a chemical element
 * Avogadro constant (NA)
 * Nucleophilic addition, a type of reaction in organic chemistry
 * Numerical aperture, a number that characterizes a range of angles in an optical system
 * nA, the symbol for nanoampere
 * Naturally aspirated engine

Biology and medicine

 * Na (tree) or Mesua ferrea, a species of tree native to Sri Lanka
 * Neuroacanthocytosis, a neurological condition
 * Nomina Anatomica, a former international standard for human anatomical nomenclature
 * Noradrenaline, a hormone
 * Nucleic acid analogue, compounds analogous to naturally occurring RNA and DNA

Current

 * Namibia (ISO country code)
 * Naples (car number plate code: NA), Italy
 * North America, a continent
 * North Africa, a subcontinent

Historical

 * Netherlands Antilles (former international vehicle registration code: NA)
 * Na (Chinese state), a small state of the Chinese Zhou dynasty from the 11th to 8th centuries BC
 * Nakoku, or Na, a state in Kyūshū, Japan from the 1st to early 3rd centuries AD

Names and titles

 * Na (羅), a Korean surname related to the Chinese surname Luo
 * Na, a particle used in Thai noble names
 * National Academician, a member of the National Academy of Design

Art and entertainment

 * Na (drum), a drum played by Tibetan shamans
 * Nahal, Shine's pet Bengal tiger on the Nick Jr. TV show Shimmer and Shine
 * New adult fiction, fiction marketed to people 18–30 years old
 * Virgin New Adventures, a series of Doctor Who novels
 * Na (EP) by Nayeon, 2024

Transport

 * NA, the tailcode of VFA-94
 * Nepal Airlines, the national flag carrier airline of Nepal
 * North American Airlines (IATA code: NA)
 * Naturally aspirated engine
 * NA MX-5 Miata, the first generation of the Mazda Miata

Language

 * Na (cuneiform), a cuneiform sign
 * Na (Javanese) (ꦤ), a letter in the Javanese script
 * Na (kana), a Japanese kana
 * Na dialect, a Sino-Tibetan variety of India
 * Na language (Narua), a Sino-Tibetan language of Yunnan, China
 * Nauruan language (ISO code: na)

Organizations

 * Narcotics Anonymous (NA), a twelve-step program that focuses on recovery from drug addiction
 * National Alliance (Latvia), a Latvian political party
 * National Alliance (Netherlands), a former Dutch political party
 * National Association (disambiguation)
 * National Association of Professional Base Ball Players, the first professional baseball league
 * Nepali Army, the land military force of Nepal
 * Neurotics Anonymous (N/A), a program for recovery from mental and emotional illness

Other uses

 * .na, the top-level domain for Namibia
 * N/A, meaning not applicable, not available, or no answer
 * N.A., the official designation of federally chartered banks in the United States
 * Mosuo or Na, an ethnic group in China near Tibet
 * Na people, an ethnic group in India
 * National Archives, the archives of a country