# L (disambiguation)

L, or l, is the twelfth letter of the English alphabet.
L or l may also refer to:

## Units of measurement and currency

* L, Langmuir (unit), a unit of exposure to a surface
* L, length in general (often the longest dimension, as opposed to width, height, or depth)
** Horse length, used in horse racing
** Boat length, used in rowing
* L, l or ℓ, litre unit
* Ancient Roman libra (translated as "pound"), a weight measure with derivative units denoted with "L" or a derived character:
** Pound (currency), a number of currencies from the British Empire, abbreviated £ or (historically) "l", "L", or "${\mathfrak {L}}$". (Some fonts use a two-bar version resembling the lira sign ₤.)
** Livre (disambiguation), a number of currencies from the French Empire, with the original abbreviated "£", "₶", or "lt"
** Lira, a number of currencies from Italy and the Ottoman Empire, abbreviated as ₤
* Leaf (books) ("l." or ℓ), an alternate numbering for books, in contrast to "p." for pages
* Specification for a line of text, for example "l. 3" is the third line of text

## Science
### Mathematics

* L, constructible universe, a particular class of sets which can be described entirely in terms of simpler sets
* L-function
* Laplace transform
* ${\mathcal {L}}$, likelihood function
* ℓ$^p$ space, the space of sequences with a finite p-norm
* L$^p$ space, a function space defined using a natural generalization of the p-norm for finite-dimensional vector spaces

### Computing

* L (complexity), a complexity class in computational complexity theory
* L-notation, a notation for running times of subexponential algorithms, often used in number theory
* L – A Mathemagical Adventure, a 1984 computer game
* Android L, code name for Android Lollipop

### Physics

* Angular momentum
* Inductance, the ratio of the magnetic flux to the current in an electrical circuit
* Latent heat
* Luminosity
* Mean free path, the average distance traveled by a moving particle between successive collisions
* Class L, a stellar classification
* Galactic longitude (l), in the galactic coordinate system

### Chemistry

* l, abbreviation for liquid
* Avogadro constant, in some German scientific literature
* Leucine, an α-amino acid
* $_L$- prefix, a levorotatiory compound
* Lewisite, a blister agent

### Biology

* Carl Linnaeus, in botanist author citations (L.)
* Haplogroup L (Y-DNA)
* Vertebra in the lumbar region of the spinal cord
* ATC code L Antineoplastic and immunomodulating agents, a section of the Anatomical Therapeutic Chemical Classification System

### Meteorology

* Low-pressure area

## Music

* L (French singer), French singer-songwriter
* L (South Korean singer), vocalist of Korean boy band Infinite
* L Marshall, British singer credited as L on the Wretch 32 song "Traktor"
* Lesure Number, music catalogue identifier for the compositions of Claude Debussy
* L Number, classification of the compositions of Franz Benda according to the catalogue of Douglas A. Lee

### Albums

* L (Godley & Creme album) (1978)
* L (Ayumi Hamasaki EP) (2010)
* L (Steve Hillage album) (1976)
* L (Candy Lo EP) (2008)
* L (Moe album) (2000)

## Vehicles and transportation

* L (Los Angeles Railway)
* Chicago "L", a rapid transit system in Chicago
* L (New York City Subway service)
* L Line (Los Angeles Metro)
* L (SEPTA Metro)
* Transilien Line L, a line of the Paris transport network
* The official West Japan Railway Company service symbol for:
** Maizuru Line.
** Uno Line.
* L-plate, a plate for learning drivers under instruction
* L Taraval (San Francisco Muni)
* Nissan L engine
* L, the low gear of an automatic transmission
* LB&SCR L class, a British tank locomotive on the London, Brighton, and South Coast Railway

## Companies and organisations

* L. Inc., California-based corporation that makes organic personal care products
* Liberals (Sweden), a political party in Sweden
* Loews Corporation, by NYSE ticker symbol
* Miscellaneous, when used as the fifth letter or behind-the-dot notation on the NASDAQ and NYSE ticker symbols

## Language and literature

* 50 (number), in Roman numerals
* [ʟ], the velar lateral approximant (IPA notation)
* [l], the alveolar lateral approximant (IPA notation)
* The Cyrillic palochka (ӏ)
* The "low" or common language in a diglossia
* ${\mathfrak {L}}$, a siglum for the Vetus Latina version of the Bible
* L (novel), a 1999 novel by Erlend Loe
* L (Death Note), a character from the Death Note manga series

## Places

* L postcode area, for Liverpool
* L Island, former name for Scawfell Island, Queensland, Australia
* L, the military time zone code for UTC+11:00

## Other uses

* Lucius (praenomen), a Roman praenomen
* Left (direction)
* L, a rating of the Brazilian advisory rating system
* L (film), a 2012 Greek film
* Lucifer (2019 Indian film), abbreviated simply as L
* L, production code for the 1965 Doctor Who serial The Rescue
* Canon L lens
* Latina Televisión, a Peruvian television channel
* Internet slang for losing