A laboratory is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed.

A labyrinth seal is a type of mechanical seal that provides a tortuous path to help prevent leakage.

Steps used aboard ship in place of stairs. The angle of inclination for a vertical ladder should be between 75–90 degrees. Continuous ladders should not exceed 9.1m (30 ft) in height.

A laddermill kite system is an airborne wind turbine consisting of a long string or loop of power kites.

An insulating material applied to surfaces of pipes, or the boiler casing in order to reduce heat transfer.

Ships not in active service; a ship which is out of commission for fitting out, awaiting better markets, needing work for classification, etc.

A type of ship which trades only in the Great Lakes of North America. They usually carry grain and ore cargoes.

In fluid dynamics, laminar flow is characterized by fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing.

An excessively large, laminar, non-metallic inclusion, producing a defect appearing in sheets or strips as segregation or in layers. Severe lamination can be repaired by a local insert plate.

Landfill gas is a mix of different gases created by the action of microorganisms within a landfill as they decompose organic waste, including for example, food waste and paper waste. Landfill gases have an influence on climate change.

Landfill gas utilization is a process of gathering, processing, and treating the methane or another gas emitted from decomposing garbage to produce electricity, heat, fuels, and various chemical compounds. After fossil fuel and agriculture, landfill gas is the third largest human generated source of methane.

Prominent objects on land (churches, towers, high buildings, etc.), beacons and lighthouses serving as guides to steer by, when approaching an estuary, river or harbour.

The langley (Ly) is a unit of heat transmission, especially used to express the rate of solar radiation (or insolation) received by the earth.

A joint between two overlapping members in parallel plane.

Larderello is a frazione of the comune of Pomarance, in Tuscany in central Italy, renowned for its geothermal productivity.

The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider and the largest machine in the world.

A collection of methods used for energy storage on a large scale within an electrical power grid.

Tanks that can be built on surface and covered with soil.

Laser isotope separation, or laser enrichment, is a technology of isotope separation using selective ionization of atoms or molecules by the means of precisely tuned lasers.

A barge carrier designed to act as a shuttle between ports, taking and discharging barges (lighters). The ship is provided with massive crane which loads and discharges the lighters over the stern.