| LEP | Light Emitting Polymer |
| LER | Lissajous Electron Plasma |
| LF | Laminar Flow |
| LFL | Lower Flammable Limit |
| LFT | Ligand-Field Theory |
| LGE | Light Generation Efficiency |
| LGQ | Linear Gaussian quadratic |
| Li | Lithium |
| LI | Laser Interferometry |
| LIC | Linear Integrated Circuit |
| LID | Leadless Inverted Device |
| LIDAR | LIght Detection And Ranging technology |
| LIF | Low Insertion Force |
| LIFO | Last In, First Out |
| LIMA | Laser-Induced Mass Analysis |
| LIMS | Laser-Induced Mass Spectrometry |
| LIR | Location Inventory Report |
| LJ | Lennard Jones (potential) |
| LKDM | Low k Dielectric Material |
| LLCC | Leadless Chip Carrier |
| LLD | Lower Limit of Detection |
| LLM | Local Linear Models |
| LLNL | Lawrence Livermore National Laboratory |
| LLNQ | Least Lots Next Queue |
| LLR | Large Lattice Relaxation |
| LLS | Localized Light Scatterer |
| LM | Light Microscopy |
| LMC | Least Material Condition |
| LMMA | Laser Microprobe Mass Analysis |
| LMTO | Linear Muffin-Tin Orbital |
| LN | Liquid Nitrogen (temperature) |
| LNA | Low Noise Amplifier |
| LNDF | Linear Natural Density Filter |
| LO | Local Oscillator |
| LOC | Level Of Concern |
| LOCOS | LOCal Oxidation of Silicon |
| LOI | Letter Of Intent |
| LOS | Loss Of Selectivity |
| LP | Local Pair |
| LPC | Linear Predictive Coding; Laser Particle Counter; Low Particle Concentration; Liquid-borne Particle Counter |
| LPCVD | Liquid Phase Chemical Vapour Deposition; Low Pressure CVD |
| LPD | Light Point Defect; Laser Projection Display |
| LPE | Liquid Phase Epitaxy |
| LPI | Low-Pressure Isolation |
| LPISM | Liquid Photo-Imageable Solder Mask |
| LPSM | Levenson Phase Shift Mask |
| LPV | Low-Pressure Vent |
| Lr | Lawrencium |
| LRP | Long Range Plan |
| LRS | Laser Raman Spectroscopy |
| LRU | Lowest Replaceable Unit |
| LS | Low-power Schottky |
| LSB | Least Significant Bit |
| LSE | Latex Sphere Equivalent |
| LSHI | Large-Scale Hybrid Integration |
| LSI | Large-Scale Integration |
| LSM | Laser Scanning Microscope |
| LTC | Lithographic Test Chip |
