Definition of Flood
An inundation of water over land not usually covered by it. Water which inundates area of surface of earth where it ordinarily would not be expected to be. Stover v. U. S., D.C.Cal., 204 F.Supp. 477, 485. See also Act of God; Flood water.
Ordinary and extraordinary floods. Extraordinary or unprecedented floods are floods which are of such unusual occurrence that they could not have been foreseen by men of ordinary experience and prudence. Ordinary floods are those, the occurrence of which may be reasonably anticipated from the general experience of men residing in the region where such floods happen.
That's the definition of Flood in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.