(1):

(n.) The act of making bright, or the state of being made bright; enlightenment; brightening, as of the mental powers.

(2):

(n.) A discharge of atmospheric electricity, accompanied by a vivid flash of light, commonly from one cloud to another, sometimes from a cloud to the earth. The sound produced by the electricity in passing rapidly through the atmosphere constitutes thunder.

(3):

(vb. n.) Lightening.