from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An abrupt, discontinuous natural electric discharge in the atmosphere.
- n. The visible flash of light accompanying such a discharge.
- n. Informal A sudden, usually improbable stroke of fortune.
- intransitive v. To discharge a flash of lightning.
- adj. Moving or occurring with remarkable speed or suddenness.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The flash of light caused by the discharge of atmospheric electrical charge.
- n. The discharge of atmospheric electrical charge itself.
- n. Anything that moves very fast.
- adj. Extremely fast or sudden.
- adj. Moving at the speed of lightning.
- v. To produce lightning.
from the GNU version of the Collaborative International Dictionary of English
- 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.
- n. The act of making bright, or the state of being made bright; enlightenment; brightening, as of the mental powers.
- v. Lightening.
from The Century Dictionary and Cyclopedia
- n. A becoming light or bright; a flashing of light: in this sense usually lightening.
- n. A sudden illumination of the heavens caused by the discharge of atmospheric electricity from one cloud to another or from a cloud to the earth; a flash of light due to electricity in the atmosphere.
- n. A becoming light or less heavy; an exhilaration of the spirits.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. abrupt electric discharge from cloud to cloud or from cloud to earth accompanied by the emission of light
- n. the flash of light that accompanies an electric discharge in the atmosphere (or something resembling such a flash); can scintillate for a second or more
Middle English, gerund of lightnen, to illuminate, from lighten, from Old English līhtan.(American Heritage® Dictionary of the English Language, Fourth Edition)
light(e)n + -ing (Wiktionary)