| l | Litre |
| L-Band | 1 530 to 2 700 MHz |
| L/D | Lift-to-drag ratio (aircraft) |
| LAB | Low-altitude bombing |
| LAD | Light aid detachment |
| LADS | Limited air defence system |
| LAFB | Light assault floating bridge |
| LAFT | Light aircraft flying training |
| Lakh | 100 000 |
| LAMPS | Light airborne multi-purpose system |
| LAMS | Local area missile system |
| LAN | Local area network (communications) |
| LANBY | Large automatic navigation buoy |
| LANTIRN | Low-altitude navigation targeting infra-red for night |
| LAPES | Low-altitude parachute extraction system |
| LAR | Local acquisition radar |
| LARS | Laser-aided rocket system |
| Low-altitude radar system |
| LAS | Large astronomical satellite |
| Low-altitude satellite |
| laser | Light amplification by stimulated emission of radiation |
| LASSM | Lightweight anti-surface ship missile |
| LAT | Local apparent time |
| Lowest astronomical tide |
| lat | Latitude |
| LAV | Light armoured vehicle |
| LAW | Light anti-tank weapon |
| LB | Locator beacon |
| lbf/in2 | Pounds force per square inch (1 lbf/in2 = 6 894.76 Pa = 0.070 kg/cm2) |
| LCA | Launch control area |
| LCAC | Landing craft, air cushion |
| LCAR | Low-coverage acquisition radar |
| LCC | Life cycle cost |
| Logistic co-ordination centre |
| LCD | Liquid crystal display |
| LCE | Latest cost estimate |
| LCN | Load classification number |
| Logistic support analysis control number |
| LCOS | Liquid crystal on silicon (display screen) |
| LCP | Landing craft, personnel |
| Launch control post (missile) |
| Leased circuits program |
| LCSS | Land combat support system |
| LCT | Landing craft, tank |
| LCVP | Landing craft, vehicles and personnel |
| LD | Load device (air cargo) |
| LDA | Landing distance available |
| LDCN | Local data communications network |
| ldg | Landing |
| LE | Leading edge (aircraft) |
| Linear error |
| LED | Light-emitting diode |
| LEL | Lower explosive limit |
| LEMP | Low-altitude magnetic pulse (nuclear explosion) |
| LEOS | Low earth orbit satellite |
| LEP | Light-emitting polymer |
| LERX | Leading edge root extension |
| LES | Land earth station (satellite) |
| LEV | Low-emitting vehicle |
| LEX | Leading edge extension (wing) |
| LF | Low frequency (30 to 300 kHz) |
| LFA | Local flying area |
| LFL | Lower flammable limit |
| LFS | Low-flying section |
| LGB | Laser-guided bomb |
| lgt | Light (or lighting) |
| LH | Left-hand |
| LHA | Local hour angle (nav) |
| LHC | Large hadron collider (physics) |
| LIC | Low-intensity conflict |
| LID | Lift improvement device |
| LIDAR | Light detecting and ranging |
| LIFO | Last in, first out |
| LIMS | Laboratory information management system |
| LINS | Loran inertial navigation system |
| LIP | Long-term infrastructure programme |
| LISA | Laser interferometric space antenna |
| Lisp | List processing (computer) |
| LIT | Longitude in time (nav) |
| LITAS | Low-intensity two-colour approach slope indicator |
| LITI | Laser-induced thermal imaging |
| LITS | Logistic information technology system |
| Logistics information technology strategy |
| LJF | Least-jammed frequency |
| LL | Load line |
| LLAD | Low-level air defence |
| LLP | Long lines program |
| LLRS | Low-level radar system |
| LLTR | Low-level transit route |
| LLTV | Low-light television |
| LLWAS | Low-level windshear alert system |
| LLWSAS | Low-level wind shear alert system |
| LMG | Light machine gun |
| LML | Lightweight multiple launcher (missile) |
| LMR | Living marine resources |
| LMT | Local mean time |
| LN | Liquid nitrogen |
| LNG | Liquefied natural gas |
| LNGC | Liquefied natural gas carrier |
| LNO | Limited nuclear option |
| LO | Landing order |
| Liaison officer |
| Lubricating oil |
| LOA | Length over all |
| LOC | Lines of communication |
| LOCPOD | Low-cost powered dispenser |
| LOFAR | Low-frequency analysis and recording |
| LOFT | Line-oriented flight training |
| log | Common logarithm |
| Logistics |
| LOH | Light observation helicopter |
| LOI | Letter of intent |
| LOMEZ | Low missile engagement zone |
| long | Longitude |
| LOP | Line of position (nav) |
| Local operations plot |
| LOPAR | Low-power acquisition radar |
| LORA | Level of repair analysis |
| LORADS | Long-range radar and display system |
| Loran | Long-range air navigation |
| LOROP | Long-range oblique photography |
| LOS | Line-of-sight |
| LOVA | Low-vulnerability ammunition |
| LOX | Liquid oxygen |
| LP | Linear programming |
| Low pressure |
| LPD | Labelled plan display (radar) |
| Landing platform, dock |
| LPG | Liquefied petroleum gas |
| LPH | Landing platform, helicopter |
| LPI | Low probability of intercept |
| LPL | Landing platform, logistic |
| LPPS | Low-pressure pump station |
| LR | Lloyd´s Register |
| Long range |
| LRBM | Long-range ballistic missile |
| LRC | Logistics readiness centre |
| LRD | Laser ranger/designator |
| LRF | Laser rangefinder |
| LRINF | Long-range intermediate nuclear forces |
| LRMR | Long-range maritime reconnaissance |
| LRMTS | Laser ranger and marked target seeker |
| LRNC | Long reference number code |
| LRRC | Long-range raiding craft |
| LRRS | Long-range radar station |
| LRSOM | Long-range stand-off missile |
| LRSP | Long-range security programme |
| LRTNF | Long-range theatre nuclear forces |
| LRU | Line-replaceable unit |
| LSA | Life saving appliance |
| Logistic support analysis |
| LSAP | Logistic support analysis plan |
| LSAR | Logistic support analysis record |
| LSB | Lower side band (radio) |
| LSD | Logistic support date |
| LSF | Logical software function |
| LSI | Large-scale integration (electronics) |
| LSL | Landing ship, logistic |
| LSOH | Low smoke, zero halogen (plastics material) |
| LSS | Logistics support system |
| LST | Landing ship, tank |
| Lightweight satellite terminal |
| LSW | Light support weapon |
| LT | Local time |
| Lt | Light |
| Ltd | Limited |
| LTDP | Long-term defence programme |
| LTG | Local tactical grid |
| LTISS | Long-term in-service support |
| LTM | Laser target marker |
| Load ton mile |
| LTPA | Long-term planning area |
| LTPG | Long-term planning guideline |
| ltr | Lighter |
| LTT | Limited technology transfer |
| LV | Light vessel |
| LVDT | Linear variable differential transformer |
| Linear variable displacement transducer |
| LW | Long wave (radio) |
| Low water |
| LWD | Low water datum |
| LWIR | Long-wave infra-red |
| LWL | Length on water line |
| Load water line |
| LWR | Laser warning receiver |
| LWT | Landing weight |
| LZ | Landing zone |
