/luyt"ning/ , n. , v. , lightninged, lightning , adj.
n.
1. a brilliant electric spark discharge in the atmosphere, occurring within a thundercloud, between clouds, or between a cloud and the ground.
v.i.
2. 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.
adj.
3. of, pertaining to, or resembling lightning, esp. in regard to speed of movement: lightning flashes; lightning speed.
[ 1350-1400; ME, var. of LIGHTENING. See LIGHTEN 1 , -ING 1 ]