| Acronym | Meaning |
| LARVA | Light-absorption Ratio Variation Approach |
| LAS | Laser Absorption Spectroscopy |
| LAS | Linear Alkylbenzene Sulfonates (anionic Surfactants) |
| LASA | Lidar Atmospheric Sounder And Altimeter |
| LASCO | Large Angle Spectroscopic Coronograph |
| LASCR | Light-activated Silicon Controlled Rectifier |
| LASCS | Light-activated Silicon Controlled Switch |
| LASE | Lidar Atmospheric Sensing Experiment |
| LASER | Light Amplification By Stimulated Emission Of Radiation |
| LASIK | Laser-assisted In Situ Keratomileusis |
| LASP | Laboratory For Atmospheric And Space Physics |
| LASS | Laser-assisted Spark Spectroscopy |
| LAST | Lowest Anticipated Service Temperature |
| LASTO | Linear Augmented Slater-type Orbital (for Electronic Structure) |
| LAT | Latency-associated Transcript |
| LAT | Linker For Activation Of T Cells |
| LATS | Long-Acting Thyroid Stimulator |
| LAW | Low-activity Waste |
| LAWG | Laboratory Accreditation Working Group |
| LAWS | Laser Atmospheric Wind Sounder (NASA) |
| LAXRD | Low-angle X-ray Diffraction |
| LAXS | Large-angle X-ray Scattering |
| LBD | Ligand Binding Domain |
| LBE | Lance Bubbling Equil. |
| LBF | Local Basis Function Method (for Solid State Band Structure) |
| LBIC | Light Beam Induced Current |
| LBM | Laser Beam Machining |
| LBO | Localized Born-Oppenheimer |
| LBP | Lipopolysaccharide-binding Protein |
| LBSF | Local Back Surface Field (solar Cells) |
| LBW | Laser-beam Welding |
| LBZ | Local Brittle Zone |
| LC | Lethal Concentration |
| LC | Liquid Chromatography |
| LC-ESI-MS/MS | Liq. Chromatog.-electrospray Ionization-tandem Mass Spectrometry |
| LCA | Life Cycle Assessment |
| LCAO | Linear Combination Of Atomic Orbitals |
| LCAO CO | Linear Combination Of Atomic Orbitals Crystal Orbital |
| LCAO LDA | LCAO-local Density Approxn. |
| LCAO LSD | Linear Combination Of Atomic Orbitals-local Spin Density |
| LCAS MS | Linear Combination Of Atomic Spinors-molecular Spinors |
| LCAT | Lecithin-cholesterol Acyltransferase |
| LCBO | Linear Combination Of Bloch Orbital |
| LCBO | Linear Combination Of Bonding Orbitals |
| LCC | Leadless Chip Carrier |
| LCCA | Linearized Coupled-cluster Approach |
| LCCC | Liquid Chromatography At The Critical Condition |
| LCCD | Linear Coupled-cluster (method With) Double (excitations) |
| LCCM | Linearized Coupled Cluster Method |
| LCCO | Light Catalytic Cycle Oil |