abyss abyss /əˈbɪs/

noun

1. () A bottomless gulf or pit; any unfathomable (or apparently unfathomable) cavity or chasm or void extending below (often used figuratively)  ( abysm , abyss )
   a bottomless gulf or pit; any unfathomable (or apparently unfathomable) cavity or chasm or void extending below (often used figuratively)
     Explorers gazed into the vast abyss, their hearts pounding with a mix of excitement and trepidation.
   Explorers gazed into the vast abyss, their hearts pounding with a mix of excitement and trepidation.