borrowed (with later spelling-pronunciation of s) from Anglo-French & Middle French abysme (compare Middle English abyme from Anglo-French abime, abisme), going back to Old French abysme, going back to Vulgar Latin *abismus, alteration of Late Latin abyssusabyss, perhaps via abÃss(i)mus, alteration by haplology of abyssÃssimus, a superlative derivative from abyssus
