noun
Literary or formal word for a very deep, dark place, often used metaphorically for something profound or unfathomable.
彼は深淵をのぞき込むように、暗い谷底を見つめた。
He stared into the dark valley floor as if peering into an abyss.
その哲学書は人間の心の深淵に
That philosophy book delves into the abyss of the human mind.
Compound of 深 (deep) and 淵 (abyss, deep pool). The kanji combination directly conveys the meaning of a deep, dark place.