ger·und

ger·und (jĕr'ənd)
n. (Abbr. ger.) Grammar.
In Latin, a noun derived from a verb and having all case forms except the nominative.
In other languages, a verbal noun analogous to the Latin gerund, such as the English form ending in -ing when used as a noun, as in singing in We admired the choir's singing.
ge·run'di·al (jə-rŭn'dç-əl) adj.
--------------------------------------------------------------------------------
The American Heritage® Dictionary of the English Language, Third Edition Copyright © 1992, 1996 by Houghton Mifflin Company. All rights reserved.


But isn't it a bit more complicated in actual English (rather than the Let's-Pretend-It's-Really-Latin of so many prescriptivists)? Surely lighting is a gerundial form of a word that was originally a noun that was then verbed...