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Light cruiser
A light cruiser is a warship carrying guns of 6.1-inch (155 mm) caliber or smaller, a category created by the London Naval Treaty of 1930 to distinguish it from heavy cruisers.
Light fixture
A light fixture, also called a light fitting or luminaire, is a complete lighting unit holding a light source plus parts to distribute, protect, and power it.
Light gun
A light gun is a gun-shaped video game controller that senses light from a CRT display to determine where the player's shot landed, as with the NES Zapper.
Light machine gun
A light machine gun (LMG) is a fully automatic, magazine or belt-fed firearm light enough for one soldier to carry and fire, giving infantry squads sustained suppressive fire.
Light pen
A light pen is a pen-shaped input device that selects positions directly on a CRT screen by detecting the display's scanning electron beam, developed at MIT around 1952.
Light Phone III
The Light Phone III is a minimalist 5G phone by Brooklyn-based Light, launched in 2025, offering calls, texts, and tools but no apps or browsing.
Light rail
Light rail, or light rail transit (LRT), is a form of urban rail transit using electric single cars or short trains, with capacity between buses and metros.
Light Rail (轻铁) (MTR)
Light Rail (轻铁) is an at-grade light rail system serving Tuen Mun, Yuen Long, and Tin Shui Wai in Hong Kong's northwestern New Territories, opened in 1988.
Light rail in Sydney
Light rail in Sydney, also known as the Sydney light rail network, is a tram network of four lines across the inner west, city center, and Parramatta, returning trams to Sydney in 1997.
Light shelf
A light shelf is a horizontal baffle part way up a window that reflects sunlight onto the ceiling, carrying daylight deeper into a room while shading the window below.
Light soaking-induced efficiency improvement (photo-brightening) in perovskite solar cells
Light soaking-induced efficiency improvement, or photo-brightening, is the largely reversible rise in efficiency of a perovskite solar cell under prolonged illumination, driven by ion migration and defect passivation.
Light steel framing
Light steel framing, also known as light gauge or cold-formed steel framing, is a building system of thin galvanized steel C and Z sections for walls, floors, and roofs, widely used in residential and modular construction.
Light switch
A light switch, also called a wall switch, is an electrical device that opens and closes a lighting circuit, ranging from toggles to dimmers and smart switches.
Light tank
A light tank is a tank that trades protection and often gun power for mobility, used for reconnaissance and infantry support from the Renault FT onward.
Light tube (daylighting)
A light tube, also called a tubular daylighting device or tubular skylight, is a passive device that carries daylight from a roof dome through a reflective tube into a room.
Light well
A light well is a vertical shaft within or beside a building, open to the sky or skylight-roofed, that delivers daylight to interior spaces windows cannot reach.
Light Years Beyond (光年之外)
Light Years Beyond (光年之外) was a Chinese AI startup founded in 2023 by Meituan co-founder Wang Huiwen to build AGI, and was acquired by Meituan within four months.
Light-activated shape memory polymers
Light-activated shape memory polymers (LASMPs) are shape memory polymers whose temporary shape recovers to the permanent shape under light, by photochemical switching or embedded photothermal fillers.
Light-emitting diode
A light-emitting diode (LED) is a semiconductor device that emits light when current passes through it; the first practical visible LED was made by Nick Holonyak Jr. in 1962.
Light-induced degradation
Light-induced degradation (LID) is a loss of conversion efficiency in crystalline silicon solar cells under illumination, mainly from a boron-oxygen defect, costing up to about 2% efficiency.
Light-sport aircraft
A light-sport aircraft (LSA) is a United States category of small, simple aircraft certificated by the FAA against industry consensus standards rather than full type certification, created in 2004.
Light-weight Linux distribution
A light-weight Linux distribution, also called a lightweight Linux distro, is built to run on little memory, disk space, and processing power, suiting old hardware.
Lightbridge (company)
Lightbridge Corporation, formerly Thorium Power, is an American nuclear fuel technology company in Reston, Virginia, developing a helical-cruciform metallic uranium-zirconium fuel for existing light water reactors and small modular reactors.
Lightdash
Lightdash is an open-source BI platform built on dbt, founded 2020 by Chaudhary and Laslett, YC S20, London. Serves dbt metrics as dashboards; $8.4M (2022), $11M Series A (Accel, 2024).
Lighter
A lighter is a portable flame-producing device used to ignite cigarettes, candles, and stoves, burning butane or naphtha; the first lighter was Döbereiner's lamp of 1823.
LightGBM
LightGBM is an open-source gradient boosting framework that builds decision tree ensembles for classification, regression, and ranking, introduced by Guolin Ke and colleagues in 2017.
Lighthill–Whitham–Richards model
The Lighthill–Whitham–Richards model, or LWR, is a first-order macroscopic traffic flow model, also known as kinematic wave theory, proposed by Lighthill and Whitham in 1955.
Lighthouse
A lighthouse is a tower carrying a light that aids maritime navigation, warning mariners of coasts, reefs, and rocks; mariners have used lights for over 2,000 years.
Lighthouse automation
Lighthouse automation is the replacement of resident lighthouse keepers with self-operating equipment and periodic maintenance visits, carried out through national programs from the 1960s through the 1990s.
Lighthouse keeper
A lighthouse keeper, also called a lightkeeper, was a person employed to operate and maintain a lighthouse, keeping its light and fog signal working so mariners could avoid dangerous coasts.