spat: English has three words spat (not counting the past form of spit). The oldest, ‘young of an oyster or similar shellfish’ [17], comes from Anglo-Norman spat, but the origins of that are unknown. Spat ‘shoe covering’ [19] is short for the earlier spatterdash [17]. This was a compound formed from spatter [16] (a word based ultimately on the sound of spattering) and dash (used here in the now archaic sense ‘splash violently’). Spat ‘tiff’ [19] originated in the USA, but its ancestry is not known.
"short gaiter covering the ankle" (usually only in plural, spats), 1779, shortening of spatterdash "long gaiter to keep trousers or stockings from being spattered with mud" (1680s), from spatter and dash (v.).
