abyss

/əˈbɪs/
noun
  1. A very deep hole or space that seems to have no bottom.
    • He dropped his phone into the abyss between the rocks.
    • Scientists are exploring the abyss of the ocean floor.
    • The hiker stared into the dark abyss of the canyon.
  2. A situation or feeling of great emptiness, despair, or danger.
    • After losing his job, he felt like he was falling into an abyss of hopelessness.
    • Her grief was an abyss that seemed impossible to escape.
    • The country was on the brink of an economic abyss.