'Waning' means shrinking, or getting smaller, and so the moon will be waning for the rest of its orbit.

“亏”的意思是缩小，所以月亮在接下来的轨道里会变小。

The mist began to settle, and from behind the wall of mist the waning moon appeared, gloomily, lighting up something dark and terrible.

薄雾开始消散， 残月从薄雾的墙后出现， 阴郁地照亮了黑暗而可怕的东西。

He recalled that awful night with the breaking ice, the fog, and especially that waning, upturned moon which rose in the morning and lit up something dark and terrible.

他回忆起那个可怕的夜晚， 冰层破碎，浓雾弥漫，尤其是清晨升起的残月， 照亮了黑暗而可怕的事物。