The aurora borealis or aurora australis.

(astronomy, physics) A unit of length equal to the distance light travels in one hour

(idiomatic) Synonym of hold a candle

(physics) An electromagnetic wave of light. / (physics, obsolete) A wave of the luminiferous ether.

(chiefly in the plural) One of the electric lights used at Christmas to decorate a tree, house, etc.

(informal) A soldier of the light infantry.

plural of light bob

plural of light elf

An electric light that turns on to give light during a power outage.

(astronomy, physics) A unit of length equal to the distance light travels in one day