Na
Abbreviation with 7 meanings
| Stands for | Sodium |
|---|---|
| Meanings | 7 |
| Categories | Science & Engineering, Geography & Places, Organizations & Companies, Texting & Internet Slang |
| Also written | NA |
Na has seven meanings. The most common are Sodium (chemical element) and North America (region); it can also stand for Narcotics Anonymous, Namibia, Avogadro constant, Numerical aperture and New adult.
Meanings of Na at a glance
| # | Na stands for | Context |
|---|---|---|
| 1 | Sodium | Science & Engineering › Chemical Element |
| 2 | North America | Geography & Places › Region |
| 3 | Narcotics Anonymous | Organizations & Companies › Nonprofit |
| 4 | Namibia | Geography & Places › Country Code |
| 5 | Avogadro constant | Science & Engineering › Physics |
| 6 | Numerical aperture | Science & Engineering › Physics |
| 7 | New adult | Texting & Internet Slang › Fandom and Fan Fiction |
1. Sodium
Science & Engineering · Chemical Element Abbreviations · also used in medicine
Sodium is the soft alkali metal with atomic number 11 that reacts violently with water. Its compounds are far more familiar: table salt (sodium chloride), baking soda and lye. In the body, sodium ions regulate fluid balance and nerve signals, and nutrition labels list sodium in milligrams.
Example: Store Na metal under mineral oil and cut only pea-sized pieces for the water demonstration.
The symbol comes from natrium, a Neo-Latin name derived from natron, the naturally occurring soda salt used in ancient Egypt; German and Scandinavian languages still call the element Natrium. Humphry Davy isolated the metal in 1807 by electrolysis of molten caustic soda. Sodium-vapor street lamps owe their yellow-orange glow to sodium's strong emission near 589 nanometers.
2. North America (NA)
Geography & Places · Region Abbreviations
Common short form for North America in business, sports and online gaming, where NA servers and NA tournaments serve players in the United States and Canada.
Example: The game's NA servers went down for maintenance overnight.
In everyday forms NA or N/A means not applicable, so region fields should be labeled. NA is also Namibia's ISO country code. Whether Mexico counts as NA depends on the company.
3. Narcotics Anonymous (NA)
Organizations & Companies · Nonprofit Abbreviations
Twelve-step fellowship for people recovering from drug addiction, adapted from Alcoholics Anonymous, holding tens of thousands of meetings a week around the world.
Example: Her counselor suggested trying an NA meeting near the treatment center.
NA began in Southern California in 1953. Its Basic Text was first published in 1983. Unlike AA, it addresses addiction to any drug, including alcohol, rather than focusing on a specific substance. Elsewhere NA can mean "not applicable", and Na is the chemical symbol for sodium.
4. Namibia (NA)
Geography & Places · Country Code Abbreviations
Namibia, capital Windhoek, alpha-3 NAM, gained independence from South Africa in 1990. The Namib, along its coast, is considered the oldest desert on Earth.
Example: The data import listed Namibia's code NA, which the spreadsheet promptly read as a missing value.
Because NA means not applicable or not available, many programs, from R to pandas, treat a Namibia code of NA as missing data unless told otherwise. Namibia was the first country to put environmental protection in its constitution.
5. Avogadro constant (NA)
Science & Engineering · Physics Abbreviations
Number of particles in one mole of a substance, fixed exactly at 6.02214076 x 10^23 per mole since the 2019 redefinition of the SI. It links the atomic scale to everyday quantities: 12 grams of carbon-12 contains about that many atoms.
Example: Multiplying moles by NA gives 1.2 x 10^24 molecules in 2 moles of water.
Named after Amedeo Avogadro, whose 1811 hypothesis held that equal volumes of gases contain equal numbers of molecules, although he never measured the number; Jean Perrin named the constant and measured it in the early 1900s. Usually written with a subscript A. Mole Day is celebrated by chemists on October 23 from 6:02 a.m. to 6:02 p.m.
6. Numerical aperture (NA)
Science & Engineering · Physics Abbreviations
Number that describes how wide a cone of light a lens or optical fiber can collect or emit, defined as the refractive index times the sine of the half-angle of that cone. Higher NA gives brighter images and finer resolution in microscopes; oil-immersion objectives reach about 1.4.
Example: The 100x oil objective has an NA of 1.40, resolving details down to about 200 nanometers.
Ernst Abbe showed in 1873 that the finest resolvable detail is roughly the wavelength divided by twice the NA, which is why immersion oil, with a higher refractive index than air, sharpens images. Fiber-optic specifications also list NA to describe acceptance angle. Na is the symbol for sodium.
7. New adult (NA)
Texting & Internet Slang · Fandom and Fan Fiction Abbreviations · also used in entertainment
Fiction category featuring protagonists roughly 18 to 30 years old, often dealing with college, first jobs and independence. Used in publishing, BookTok and bookstores.
Example: This NA romance is set in a college dorm during senior year.
St. Martin's Press coined the term in 2009 with a contest seeking fiction for readers who had outgrown young adult (YA) books. NA is often associated with romance and more mature content than YA. Outside books, NA can mean "not applicable" or North America.
Related abbreviations
More chemical element abbreviations
- Mn – Manganese
- Mo – Molybdenum
- Mt – Meitnerium
- N – Nitrogen
- Nb – Niobium
- Nd – Neodymium
- Ne – Neon
- Nh – Nihonium
See all 118 chemical element abbreviations →