| Acronym | Meaning |
| LSRGO | Light Straight-run Gas Oil |
| LSS | Laboratory Safety System |
| LSS | Life-Span Study |
| LSS | Lindhard-Scharff-Schiott Theory |
| LSS | Laser Synchrotron Source |
| LSSV | Linear Sweep Stripping Voltammetry |
| LST | Local Solar Time |
| LST | Laser Scattering Tomography |
| LST | Light Scattering Tomography |
| LSTH | Liu-Siegbahn-Truhlar-Horowitz (potential-energy Surface) |
| LSV | Linear Sweep Voltammetry |
| LSW | Lifshitz-Slyozov-Wagner Theory |
| LSW | Localized Spherical Wave (in Electronic Structure Calcns.) |
| LT1ESWTR | Long Term 1 Enhanced Surface Water Treatment Rule |
| LT2ESWTR | Long-Term 2 Enhanced Surface Water Treatment Rule [of US EPA] |
| LTA | Linde Type A |
| LTAVD | Low Temperature Arc Vapor Deposition |
| LTBRM | Lanczos Tight Binding Recursion Method |
| LTCC | Low-temperature Co-fired Ceramic |
| LTDA | Low Temperature Die Attach [adhesive] |
| LTDU | Land Treatment Demonstration Unit |
| LTE | Local Thermodn. Equil. |
| LTEC | Linear Thermal Expansion Coefficient |
| LTER | Long Term Ecological Research |
| LTH | Linearized Time-dependent Hartree (approxn. |
| LTH | Luteotropic Hormone |
| LTK | Laser Thermal Keratoplasty |
| LTMED | Low Temperature Multi-effect Distillation |
| LTMLS | Low Temperature Molecular Luminescence Spectroscopy |
| LTMPF | Low-Temperature Microgravity Physics Facility |
| LTO | Laguerre-type Orbital (an Ao) |
| LTP | Leachate Treatment Plant |
| LTP | Lipid-transfer Protein |
| LTP | Long-term Potentiation |
| LTPL | Low Temperature Photoluminescence |
| LTPLD | Liquid Target Pulsed Laser Deposition |
| LTPS | Low Temperature Polysilicon |
| LTR | Long Terminal Repeat |
| LTTA | Low Temperature Thermal Aeration Process |
| LTTD | Low Temperature Thermal Desorption |
| LTTS | Low-Temperature Thermal Separation (for Waste Soil Treatment) |
| LTU | Land Treatment Unit |
| LUC | Large Unit Cell Semiempirical Approxn. (for Band Structure) |
| LUCO | Lowest Unoccupied Crystal Orbital |
| LUFT | Leaking Underground Fuel Tank |
| LULU | Locally Undesirable Land Use |
| LUMO | Lowest Unoccupied Molecular Orbital |
| LUST | Leaking Underground Storage Tank |
| LUV | Large Unilamellar Vesicle |
| LVAD | Left Ventricular Assist Device |