gas lighter than air

Short for 軽騎兵 (keikihei): light cavalry

Short for 軽機関銃 (keikikanjū, “light machine gun”); LMG

light music (such as popular songs, jazz, chanson, etc.), as opposed to classical music / semiclassical music

minor offense

light boat

small mistake

to make a small mistake / to neglect

a light vehicle, kei car, city car, (specifically) a four-wheeled passenger vehicle with engine displacement less than 660 cubic centimeters

valueless, worthless