L4

L4 or L-4 may refer to :

• SP&S Class L-4, an 1884 steam locomotives class
• USS L-4 (SS-43), a 1915 United States Navy L-class submarine
• HMS L4, a 1918 British L class submarine
• Lawson L-4, a 1924 American unflown biplane airliner
• Piper Cub (U.S. military designation: L-4), an aircraft
• Inline-four engine (L4), a type of inline internal combustion four cylinder engine
• Liberty L-4, a World War I four-cylinder, water-cooled, inline, aero-engine
• Lynx Aviation (IATA code)
• L4 (New York City bus), a temporary bus route in New York City
• L4, an S-Bahn line of the Léman Express in Switzerland and France
• Parramatta Light Rail, also known as the L4, a light rail service in Parramatta, Sydney, Australia
• Chaika L-4, a Russian twin-engined amphibious aircraft
• Soviet submarine L-4

• L4 microkernel family, a family of operating system kernels
• L4, the transport layer in the OSI model of computer communications
• L4, the fourth Lagrangian point in an astronomical orbital configuration
• L⁴, an Lp space for p=4 (sometimes called Lebesgue spaces)
• L-4, the fourth iteration of L-carrier, high capacity frequency division multiplex over coaxial cable used by the Bell System

• Haplogroup L4 (mtDNA), a human mitochondrial DNA haplogroup
• Ribosomal protein L4, a human gene
• L4, a lumbar vertebrae of the vertebral column, in human anatomy
• The fourth and last larval stage in the Caenorhabditis elegans worm development

• L4, a modern version of the Bren light machine gun in the British Army
• ISO/IEC 8859-4 (Latin-4), an 8-bit character encoding

• L04 (disambiguation)
• Level 4 (disambiguation)
• 4L (disambiguation)
• LIV (disambiguation)