| Acronym | Meaning |
| LDTOF | Laser-Desorption Time-Of-Flight Mass Spectrometry |
| LDV | Laser Doppler Velocimetry |
| LDV | Light Duty Vehicle |
| LEACH | Leaching Evaluation Of Agricultural Chemicals |
| LEACHM | Leaching Estimation And Chemistry Model |
| LEACHMP | Leaching Estimation And Chemistry Model-pesticides |
| LEAFS | Laser-Excited Atomic Fluorescence Spectrometry |
| LEAP | Local-electrode Atom Probe |
| LEAR | Low Energy Antiproton Ring |
| LEC | Light-emitting Electrochemical Cell |
| LEC | Liquid Encapsulated Czochralski |
| LECD | Lifetime Equivalent Constant Dose |
| LECIVA | Low Energy Charge-induced Voltage Alteration |
| LED | Light-emitting Diode |
| LED | Longitudinal Eddy Current Delay |
| LEDO | Limited Expansion Of Diatomic Overlap |
| LEEBI | Low Energy Electron Beam Irradiation |
| LEED | Low-energy Electron Diffraction |
| LEEIXS | Low Energy Electron Induced X-ray Spectrometry |
| LEELS | Low Energy Electron Loss Spectroscopy |
| LEEM | Low-energy Electron Microscopy |
| LEEMS | Low Energy Electron Mass Spectroscopy |
| LEEP | Low-energy Solvent Extraction Process |
| LEEPS | Low Energy Electron Point Source |
| LEERM | Low Energy Electron Reflection Microscopy |
| LEES | Local Excess-electron State (a Mol.-crystal Wave Function) |
| LEF | Large-amplitude Elec. Field Fluctuations |
| LEFI | Local Electric Field Instrument |
| LEFM | Linear Elastic Fracture Mechanics |
| LEGO | Lean Exhaust Gas Oxygen Sensor |
| LEI | Laser Enhanced Ionization |
| LEIR | Low Energy Ion Ring |
| LEIS | Low-Energy Ion Scattering Spectroscopy |
| LEISS | Low-energy Ion-scattering Spectroscopy |
| LEL | Lower Explosion Limit |
| LEL | Lowest Effect Level |
| LEMA | Least Error Matrix Analysis |
| LEMAO | Least Energy Minimal Atomic Orbital |
| LEMF | Laser-excited Molecular Fluorescence |
| LEMO | Lowest Empty Molecular Orbital (equivalent To LUMO) |
| LEMOFS | Laser-excited Molecular Fluorescence Spectrometry |
| LENA | Low-energy Neutral Atom |
| LEO | Lateral Epitaxial Overgrowth |
| LEO | Low Earth Orbit |
| LEOS | Lasers And Electro-Optics Society |
| LEP | Large Electron-Positron Collider |
| LEP | Light Emitting Polymer |
| LEP | Local Electron Pair (model For Intra- & Intermol. Interactions) |
| LEPC | Local Emergency Planning Committee |
| LEPD | Low Energy Photon Detector |