Meaning

noun a sandbank in a stretch of water that is visible at low tide

noun a stretch of shallow water

noun a large group of fish

origin1570, presumably from Middle English *schole (“school of fish”), from Old English sċeolu, sċolu (“troop or band of people, host, multitude, division of army, school of fish”), from Proto-West Germanic *skolu, from Proto-Indo-European *(s)kelH- (“to divide, split, separate”). Cognate with West Frisian skoal (“shoal”), Middle Low German schōle (“multitude, troop”), Dutch school (“shoal of fishes”).…

Etymology from Wiktionary, CC BY-SA 3.0