L1

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

Math

 * L1 distance in mathematics, used in taxicab geometry
 * L1, the space of Lebesgue integrable functions
 * ℓ1, the space of absolutely convergent sequences

Science

 * L1 family, a protein family of cell adhesion molecules
 * L1 (protein), a cell adhesion molecule
 * L1 or LINE1; transposable elements in the DNA
 * , 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

Technology

 * 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

Transportation and military

 * 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

Locomotives

 * 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

Aircraft

 * 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

Submarines

 * USS L-1 (SS-40), a 1915 United States Navy L-class submarine
 * HMS L1, a Royal Navy submarine

Other

 * 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


 * Containing L1


 * 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