1. Immeasurably deep, severe, or extreme; fathomless: "The depth of her sorrow was an abysmal situation and, as a result, she could find no expression except to cry."
2. Informal, extremely bad or of very low quality: "The teacher abhorred the abysmal behavior in her class by her students."
3. Incapable of being measured or even understood; incomprehensible, inscrutable: "Kristy felt like an abysmal failure because she couldn't remember how to spell the key word in the spelling contest."
4. Etymology: from the year 1656, formed in English from obsolete abysm, "bottomless gulf, greatest depths"; from Old French abisme, from Vulgar Latin abyssimus.