a brilliant electric spark discharge in the atmosphere, occurring within a thundercloud, between clouds, or between a cloud and the ground.

to emit a flash or flashes of lightning (often used impersonally with it as subject)

If it starts to lightning, we'd better go inside.

of, pertaining to, or resembling lightning, esp. in regard to speed of movement

lightning flashes; lightning speed.

adjective

fulgurant , fulgurous , sheet , streak

noun

fireball , levin

verb

fulgurate