abysm (n.) Look up abysm at Dictionary.com
"bottomless gulf, greatest depths," now chiefly poetic, c. 1300, from Old French abisme "chasm, abyss, depths of ocean, Hell" (12c., Modern French abîme), from Vulgar Latin *abyssimus (source also of Spanish and Portuguese abismo), which represents perhaps a superlative of Latin abyssus or a formation on analogy of Greek-derived words in -ismus; see abyss.