a. An abrupt, discontinuous natural electric discharge in the atmosphere.
b. The visible flash of light accompanying such a discharge.
2. Informal A sudden, usually improbable stroke of fortune.
intr.v. light·ninged (-nĭngd), light·ning, light·nings
To discharge a flash of lightning.
Moving or occurring with remarkable speed or suddenness.
[Middle English, gerund of lightnen, to illuminate, from lighten, from Old English līhtan; see leuk- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.