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Halligan bar
The Halligan bar, also known as the Hooligan tool, is a forcible entry tool used by firefighters, designed in 1945 by FDNY captain Hugh A. Halligan.
Hallucination (artificial intelligence)
AI hallucination is output from a generative model that looks fluent or plausible but lacks grounding in verifiable facts, ranging from minor inaccuracies to entirely fabricated content.
Hallucination in multimodal models
Hallucination in multimodal models is the generation of plausible but incorrect output, most often when vision-language models describe objects absent from an image, a major obstacle to reliable real-world use.
Halo orbit
A halo orbit is a periodic, three-dimensional orbit around a Lagrange point, first used by the ISEE-3 spacecraft in 1978 and now used by the James Webb Space Telescope.
HALO Trust
The HALO Trust is a British humanitarian organization, incorporated in 1988, that clears landmines and explosive remnants of war; described by the US State Department as the world's largest mine clearance charity.
Halo-gravity traction device
A halo-gravity traction device straightens severe spinal curves before surgery, using a halo ring pinned to the skull and weights that pull the head upward for weeks.
Halogen lamp
A halogen lamp, also called a tungsten-halogen bulb, is an incandescent lamp whose halogen cycle keeps the bulb wall clean and lets the filament run hotter than in ordinary bulbs.
Halstead complexity measures
Halstead complexity measures are software metrics introduced by Maurice Halstead in 1977 to measure program complexity, effort, and likely errors from counts of operators and operands in source code.
Halt and Catch Fire (computing)
Halt and Catch Fire (HCF) is a joke mnemonic for a machine instruction that halts a processor beyond normal recovery, first printed in a 1967 Datamation humor piece.
Halten Øst Oil and Gas Field
Halten Øst is a gas and condensate field in the Norwegian Sea east of Åsgard, combining six discoveries into one subsea development that began producing in March 2025.
Halve Maen
The Halve Maen (Half Moon) was the Dutch East India Company ship sailed by Henry Hudson up the Hudson River in 1609, opening Dutch colonization of New Netherland.
Ham House
Ham House, Richmond upon Thames: Grade I listed 1610 Jacobean mansion built for Sir Thomas Vavasour, transformed by the Duchess of Lauderdale, National Trust since 1948, with 17th-century interiors and gardens.
Hamaca Oil and Gas Field
Hamaca Oil and Gas Field is an extra-heavy oil field in Venezuela's Orinoco Heavy Oil Belt, producing upgraded Hamaca Blend crude since 2004 under PDVSA and Chevron.
Hamad International Airport (مطار حمد الدولي)
Hamad International Airport (مطار حمد الدولي) is Qatar's main international airport and the hub of Qatar Airways, opened in Doha in 2014 and serving 54.3 million passengers in 2025.
Hamada al Hamra-Az-Zawiyah Oil Pipeline
The Hamada al Hamra-Az-Zawiyah Oil Pipeline is a 387 km crude oil pipeline in western Libya, connecting the Hamada al Hamra oilfield to the Zawiya refinery.
Hamaoka nuclear power plant
Hamaoka Nuclear Power Station (浜岡原子力発電所) is a nuclear power plant in Omaezaki, Shizuoka Prefecture, Japan, owned by Chubu Electric Power, with all reactors idle since the 2011 Fukushima shutdown.
Hambach surface mine
The Hambach surface mine (Tagebau Hambach) is an opencast lignite mine in North Rhine-Westphalia, Germany, operated by RWE since 1978 and the largest lignite mine in Europe.
Hamburg America Line
The Hamburg America Line (HAPAG), formally the Hamburg-Amerikanische Packetfahrt-Actien-Gesellschaft, was a Hamburg shipping company founded in 1847, the world's largest steamship line before World War I.
Hamburg Süd
Hamburg Süd, formally the Hamburg-Südamerikanische Dampfschifffahrtsgesellschaft, was a German shipping company founded in Hamburg in 1871 to run liner services between Europe and South America.
Hamburg wheel tracking test
The Hamburg wheel tracking test is a laboratory test that rolls a loaded steel wheel over submerged hot asphalt specimens to measure resistance to rutting and moisture damage.
Hamburger button
The hamburger button, also called the hamburger icon or menu button, is a user-interface icon of three stacked lines that hides navigation behind one tap or click.
Hamburger Hochbahn
Hamburger Hochbahn AG, also known as HOCHBAHN, is Hamburg's principal public transport operator, founded in 1911 to run the city's first elevated and underground railway.
Hamburgische Schiffbau-Versuchsanstalt
The Hamburgische Schiffbau-Versuchsanstalt (HSVA), known in English as the Hamburg Ship Model Basin, is a not-for-profit hydrodynamic research organization in Hamburg, Germany, founded in 1913 and operating towing tanks, cavitation tunnels, and an ice model basin.
Hameau de la Reine
The Hameau de la Reine, or Queen's Hamlet, is a rustic model village built for Marie-Antoinette by architect Richard Mique in the Petit Trianon park at Versailles, completed in 1786.
Hami-Chongqing UHV Transmission Line power station
The Hami-Chongqing UHV Transmission Line power station is an operating 4,000 MW coal-fired power station in Barköl, Hami, Xinjiang, built as dispatchable generation backing the UHVDC line to Chongqing.
Hamilton Robotics
Hamilton Robotics is the laboratory automation business of Hamilton Company, headquartered in Reno, Nevada, selling Microlab liquid handlers, robotic platforms, and automated sample storage systems for life science laboratories.
Hamilton Watch Company
Hamilton Watch Company is an American watch manufacturer founded in 1892 in Lancaster, Pennsylvania, known for railroad-grade pocket watches, military chronometers, and the first electric wristwatch.
Hamilton-class cutter
The Hamilton class, also known as the Secretary class, was a group of twelve 378-foot high-endurance cutters built for the United States Coast Guard between 1965 and 1972.
Hamilton–Jacobi reachability analysis
Hamilton–Jacobi reachability analysis is a formal verification method that computes, for a dynamical system, the set of states from which it can reach or avoid a target region despite bounded disturbances.
Hamiltonian path
A Hamiltonian path, also called a Hamilton path, is a path in a graph that visits each vertex exactly once. The problem of finding one is NP-complete.