L1

Last updated October 20, 2025

L1, L01, L.1, L 1 or L-1 may refer to:

Mathematics, science and technology

L₁ distance in mathematics, used in taxicab geometry
L¹, the space of Lebesgue integrable functions
ℓ¹, the space of absolutely convergent sequences
Lasso (statistics), a means of regression analysis used in statistics and machine learning

L1 family, a protein family of cell adhesion molecules
L1 (protein), a cell adhesion molecule
L1 or LINE1; transposable elements in the DNA
L₁, Lagrangian point 1, the most intuitive position for an object to be gravitationally stationary relative to two larger objects (such as a satellite with respect to the Earth and Moon)
Anthranilic acid, also called vitamin L1
The first lumbar vertebra of the vertebral column in human anatomy
The first larval stage in the Caenorhabditis elegans worm development

L1, one of the frequencies used by GPS systems (see GPS frequencies)
L1, the common name for the Soviet space effort known formally as Soyuz 7K-L1, designed to launch men from the Earth to circle the Moon without going into lunar orbit
ISO/IEC 8859-1 (Latin-1), an 8-bit character encoding
An L-carrier cable system developed by AT&T
The level-1 CPU cache in a computer
Sony Xperia L1, an Android smartphone
A class of FM broadcast station in North America

Lehrgeschwader 1, from its historic Geschwaderkennung code with the Luftwaffe in World War II
Lufthansa Systems' IATA code
Lawrance L-1, a predecessor of the 1920s American Lawrance J-1 aircraft engine
L1 Dulwich Hill Line on the Inner West Light Rail, a light rail service in Sydney, Australia
L1 (New York City bus), a temporary bus route in New York City
Volkswagen L1, a Volkswagen concept hybrid car
L1A1 Self-Loading Rifle
L1, an S-Bahn line of the Léman Express in Switzerland and France

Erie L-1, an American 0-8-8-0 steam locomotive class
GCR Class 1B, latterly known as LNER Class L1, a class of British 2-6-4T steam locomotives
GNR Class L1, latterly known as LNER Class R1, a class of British 0-8-2T steam locomotives
LNER Thompson Class L1, a class of British 2-6-4T steam locomotives
NCC Class L1, a Northern Counties Committee 0-6-0 class steam locomotive
Pennsylvania Railroad class L1s, an American 2-8-2 steam locomotive class
Soo Line L-1 class, an American 2-8-2 steam locomotive class
SP&S Class L-1, an American 4-4-0 steam locomotive class
SR L1 class, a class of 4-4-0 steam locomotives of Great Britain
VR Class Vr1 (originally L1), a Finnish steam locomotive class

Arado L 1, a 1929 German two-seat parasol-wing sporting monoplane
Macchi L.1, a 1915 Austro-Hungarian reconnaissance flying boat
Stinson L-1 Vigilant, the US Army Air Forces designation for the Stinson Model 74 observation aircraft

Ligue 1, the top division of French football
Lowest unique bid
L1, in linguistics, a subject's first language or mother tongue
L-1 Identity Solutions, a US face-recognition corporation
L-1 visa, a document used to enter the United States for the purpose of work
L1, an abbreviation denoting someone is a Level 1 Judge, in reference to Magic: The Gathering
Bose L1 Portable Systems
L=1, a lunar eclipse classification on the Danjon scale
L1, the postcode for central Liverpool, a major UK city
L1 or Lucifer (2019 Indian film), a 2019 Indian political action thriller film, followed by L2: Empuraan
L1 (broadcaster), the public broadcaster for the Dutch province Limburg.

ATC code L01 Antineoplastic agents, a subgroup of the Anatomical Therapeutic Chemical Classification System
Barcelona Metro line 1
DSC-L1, a 2004 Sony Cyber-shot L series camera model
Haplogroup L1 (mtDNA), a human mitochondrial haplogroup from Africa
Luxo L-1, a lamp
Panasonic Lumix DMC-L1, a 2006 single-lens reflex camera