depths; abstruse; profound; recondite; arcana

💡 Nuance & Usage: Refers to something that is very deep, profound, or difficult to understand, often in an intellectual or abstract sense. It can be used for the core of a philosophy, the hidden parts of a forest, or the secrets of a science. It implies complexity and hidden layers. 物事の奥深く、容易には理解できない核心や、隠された部分を指す。