lonely, quiet
寞 centers on a state of stillness and isolation: a quiet, lonely emptiness where little stirs.
寞 combines 宀 (roof) with 莫, which likely contributes the sound and the idea of stillness or absence. The exact historical development is uncertain.
Under a roof 宀, the 莫 part suggests a vast, empty space where nothing moves. Picture a silent, deserted house: 寞 is the lonely quiet inside.
For バク, imagine a lonely person backing into a quiet corner: back -> バク, and the stillness of 寞 surrounds them.