Meaning of “light” - Learner’s Dictionary

light

noun uk us /laɪt/
BRIGHTNESS [ U ]

B1 the brightness that shines from the sun, from fire, or from electrical equipment, allowing you to see things:

bright/dim light
a beam/ray of light
Light was streaming in through the open door.
DEVICE [ C ]

A2 a device that produces light:

car lights
to switch/turn the light on
They must be in bed - I can't see any lights on anywhere.
a light

a flame from a match, etc used to make a cigarette start burning:

Have you got a light, please?
set light to sth mainly UK

to make something start burning

in the light of sth (also US in light of sth)

If something is done or happens in the light of facts, it is done or happens because of those facts:

The drug has been withdrawn in the light of new research.

(Definition of “light noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)