Meaning

noun (often followed by `of') a large number or amount or extent

noun a sudden forceful flow

noun the occurrence of a water flow resulting from sudden rain or melting snow

originThe noun is derived from Middle English spate, spait (“a flood”), influenced by Scots spate (“torrent of water, flood; heavy downpour of rain; (figurative) bout of drinking; large crowd of people; flood of events, words, etc.”). The further etymology of the Middle English and Scots words is uncertain; they are possibly related to English spatter and Dutch spatten (“to spatter, splash”), possibly…

Etymology from Wiktionary, CC BY-SA 3.0