# N (disambiguation)

N is the fourteenth letter of the English alphabet.
N or n may also refer to:

## Mathematics

* $\mathbb {N}$ or N, the set of natural numbers
* N, the field norm
* N for nullae, a rare Roman numeral for zero
* n, the size of a statistical sample

## Science

* ATC code N Nervous system, a section of the Anatomical Therapeutic Chemical Classification System
* Haplogroup N (mtDNA), a human mitochondrial DNA haplogroup
* Haplogroup N (Y-DNA), a human Y-chromosome DNA haplogroup
* N band, an atmospheric transmission window in the mid-infrared centred on 10 micrometres
* N ray, a hypothesized form of radiation, found to be illusory
* N., abbreviation of the Latin word nervus meaning nerve, used in anatomy, e.g. N. vagus

### Quantities and units

* N for Newton (unit), the SI derived unit of force
* N or $F_{n}$, a normal force in mechanics
* Nitrogen, symbol N, a chemical element
* N or Asn, the symbol for the common natural amino acid asparagine
* N, the Normality (chemistry) or chemical concentration of a solution
* N, the neutron number, the number of neutrons in a nuclide
* N, in Brillouin zone, the center of a face of a body-centered cubic lattice
* N, the physical quantity "rotation" in the International System of Quantities
* n, for nano-, prefix in the SI system of units denoting a factor of 10$^{−9}$
* n, the optical refractive index of a material
* n, the principal quantum number, the first of a set of quantum numbers of an atomic orbital
* n, an electron density, the measure of the probability of an electron being present at a specific location
* n, an amount of substance in chemical physics
* n, the coordination number of a substance
* n-, a lowercase prefix in chemistry denoting the straight-chain form of an open-chain compound in contrast to its branched isomer
* N-, an uppercase prefix in chemistry denoting that the substituent is bonded to the nitrogen, as in amines

## Transport

* N (New York City Subway service), a service of the New York City Subway
* N Judah, a Muni Metro line in San Francisco, California
* N (Los Angeles Railway), a line operated by the Los Angeles Railway from 1920 to 1950
* Tokyo Metro Namboku Line, a subway service operated by the Tokyo Metro, labeled
* Nagahori Tsurumi-ryokuchi Line, a subway service operated by the Osaka Metro, labeled
* Transilien Line N, a line of the Paris transport network
* , the official West Japan Railway Company service symbol for the Akō Line.

## Engineering

* N, in geotechnical engineering, the result of a standard penetration test
* N, in electrical systems, the connection to neutral
* N, an ITU prefix allocated to the United States for radio and television stations
* n (Poland), a digital TV platform
* N battery or N cell, a standard size of dry cell battery
* N connector, a threaded RF connector for joining coaxial cables

## Entertainment

* N. (novella), a 2008 short story by Stephen King
* Near (Death Note) (alias N), a character in the manga series Death Note
* N (video game), a 2005 computer game
* N (Pokémon), the leader and king of crime syndicate Team Plasma in the Pokémon franchise
* The N, a block on the Noggin TV channel
* N, the production code for the 1965 Doctor Who serial The Web Planet
* "N" Is for Noose, the fourteenth novel in Sue Grafton's "Alphabet mystery" series, published in 1998
* Serial Designation "N", one of the main characters from the webseries Murder Drones (2021-2024)

### Music

* N (singer), stage name of Cha Hak-yeon, leader of the South Korean boy band VIXX
* N, an alias of Drew Mulholland, who recorded more often as Mount Vernon Arts Lab
* N (album), a 2008 album by Norther
* "N", a song by BanYa for the "Pump It Up: The Perfect Collection" music video game
* "n", a song by iamamiwhoami

## Language

* n, the International Phonetic Alphabet symbol for a voiced alveolar nasal sound
** n̪, n̼, n̥, ɳ, ɳ̊, ɲ, ɲ̊, ŋ, ŋ̊, ɴ, symbols representing other nasal consonants in the International Phonetic Alphabet
* N (kana), a Japanese kana
* Noun, a part of speech

## Other uses

* Hyundai N, high performance brand of Hyundai Motor Company
* N, North, one of the cardinal directions of the compass
* N postcode area, the part of the London post town covering part of North London, England
* ₦, the symbol for the Nigerian naira currency
* N, the code used to denote vehicle registration plates of Norway
* N-class ferry, a class of small RORO ferry
* N scale or N gauge, a popular model railway size
* N, the identifier for the knight (chess) in algebraic notation
* November, the military time zone code for UTC−01:00
* Nachrichten-Abteilung, naval intelligence department of Imperial German