42,772 articles
Lead(II) acetate
Lead(II) acetate, also known as sugar of lead, is a colorless lead salt of acetic acid with a sweet taste once used as a sweetener in Roman wine syrup.
Lead(II) carbonate
Lead(II) carbonate, also known as lead carbonate, is a white, insoluble lead salt occurring naturally as the mineral cerussite and once widely used as a white paint pigment.
Lead(II) nitrate
Lead(II) nitrate (Pb(NO3)2), also called plumbous nitrate, is a water-soluble white crystalline salt of lead, made from lead and nitric acid and used to prepare other lead compounds.
Leader election
Leader election, also called leader finding, is a fundamental problem in distributed computing where the processes of a network single out exactly one of themselves as leader.
Leading-edge vortex
A leading-edge vortex is a spiraling region of rotating flow that forms over highly swept wings, producing extra lift called vortex lift on delta wings.
Leaf litter breakdown
Leaf litter breakdown is the decomposition of dead leaves in streams and rivers through leaching, microbial conditioning, and fragmentation, a key energy source for aquatic food webs.
League (unit)
The league is a historical unit of distance, and of land area in Spanish colonial usage, whose value varied widely; the English land league equaled 3 statute miles.
Leak detection and repair
Leak detection and repair (LDAR) is a regulatory practice in which oil and gas facilities are surveyed for methane leaks, typically with infrared cameras, and leaks are repaired within mandated deadlines.
Leakage reduction
Leakage reduction refers to the control protocols, pulse designs, and circuit insertions that return quantum computing qubits to their two computational states and prevent escape into other energy levels.
Leakage reduction units
A leakage reduction unit (LRU) is a quantum circuit that converts leakage, where a qubit escapes its two computational states, into errors that error correction can fix.
Leaking underground storage tank program
The leaking underground storage tank (LUST) program is the US federal and state program for cleaning up petroleum and hazardous releases from underground storage tanks.
Lean Six Sigma
Lean Six Sigma is a process-improvement methodology combining Lean's waste elimination with Six Sigma's statistical reduction of process variation, applied through the structured DMAIC cycle.
Leap second
A leap second is a one-second adjustment occasionally inserted into Coordinated Universal Time to keep atomic clocks aligned with Earth's rotation; it was adopted in 1972.
Leap year
A leap year, also called an intercalary or bissextile year, is a year with an extra day, February 29, added to keep the calendar aligned with the seasons.
Learned society
A learned society, also called a scholarly society or learned academy, is a non-profit organization that promotes an academic field through journals, conferences, and research funding.
Learning Assistant Model
The Learning Assistant model is an undergraduate STEM education approach in which students assist faculty in large courses, begun at the University of Colorado Boulder in 2001.
Least common multiple
The least common multiple (LCM), also called the smallest common multiple, is the smallest positive integer that two nonzero integers both divide evenly, such as lcm(6, 9) = 18.
Least count
The least count of a measuring instrument is the smallest change in the measured quantity it can resolve, such as 0.1 mm for a common vernier caliper.
Least significant difference test
The least significant difference (LSD) test, also called Fisher's LSD, is a pairwise multiple comparison procedure used after ANOVA to decide which pairs of treatment means differ significantly.
Least squares
Least squares, or the least-squares method, is a statistical estimation method that minimizes the sum of squared deviations between observed data and a model's predictions; Legendre published it in 1805.
Least-squares migration
Least-squares migration (LSM) is a seismic imaging method that iteratively inverts a forward modeling operator to produce images with fewer artifacts, truer amplitudes, and higher resolution than conventional migration.
Least-upper-bound property
The least-upper-bound property, also called the supremum property, says every nonempty subset of an ordered set that is bounded above has a least upper bound in the set.
Leave-one-out cross-validation
Leave-one-out cross-validation (LOOCV) is a resampling method that estimates a model's out-of-sample prediction error by repeatedly leaving out one observation, equivalent to k-fold cross-validation with k equal to the sample size.
Leaving group
A leaving group is an atom or group, charged or uncharged, that detaches from the main part of a substrate in a specified reaction, such as chloride in chloroalkane hydrolysis.
Lebesgue integration
Lebesgue integration is a mathematical technique that partitions a function's range instead of its domain, extending integration to functions with many discontinuities and underpinning modern probability theory.
Lebesgue measure
Lebesgue measure is the standard way of assigning length, area, and volume to subsets of Euclidean space, formulated by Henri Lebesgue in 1901 and underlying the Lebesgue integral.
Lee Alvin DuBridge
Lee Alvin DuBridge was an American experimental physicist and founding director of the MIT Radiation Laboratory during World War II, and president of Caltech from 1946 to 1969.
Lee Cronin (chemist)
Leroy "Lee" Cronin is Regius Professor of Chemistry at the University of Glasgow, working on machine learning for chemistry, the Chemputer, assembly theory, and the origin of life.
Lee cyclogenesis
Lee cyclogenesis, also called orographic cyclogenesis, is the development of a cyclone on the downwind side of a mountain range, such as the Alps or Rockies.
Lee Greenawald
Lee Greenawald is an American occupational safety scientist and analytical chemist who led NIOSH's respirator testing branch, researched fentanyl protection through gloves, and received a PECASE in 2025.