- least action
- leaving gas
- leblanc connection
- left-handed
- legitimacy
- lepton conservation
- Lauritsen electroscope
- lead
- lead equivalent
- leaden
- leading phase
- leak resistance
- leakage
- leakage conductance
- leakage indicator
- Leidenfrost point
- level correlation
- level line
- level meter
- level regulator
- level vessel
- lever arm
- lever switch
- leverage
- Lewis modulus
- Lewis number
- leyden jar
- libration
- life expectancy
- leakage factor
- leakage inductance
- leakage radiation
- leakproof design
- least temperature
- leavings
- LED device
- leg
- Legendre function
- legitimate
- lengthened
- lens carrier
- lepton field
- Leslle cube
- lethargy
- level control
- level controller
- levelling instrument
- levitation
- levogyration
- lewis correlation
- Lichenberger figures
- light bulb
- light impact
- light load
- light maser
- light mason
- light microsecond
- light particle
- light pressure
- light refrigerant
- light relay
- light spot
- light transmission
- light-tight
- light-weight
- lighter
- lightguide
- lighting load
- lighting main
- lighting mains
- lighting tariff
- lightning discharge
- lightning impulse
- lightning strike
- limit switch
- limited response
- limiting diode
- limiting voltage
- Lindeck potentiometer
- line intensity
- line lengthener
- line location
- line loss
- line speed
- line tuning
- limit thermostat
- limiting mains
- Lindemann electrometer
- Lindhard region
- line
- line balance
- line cord
- line drop
- line filter
- line influence
- line rate
- line scanning
- line side
- line signal
- linear accelerator