Nocturnal means occurring at night.
The dog's main duty will be to accompany me on long nocturnal walks.
那只狗的主要职责将是陪我走长途夜路。
Nocturnal creatures are active mainly at night.
When there is a full moon, this nocturnal rodent is careful to stay in its burrow.
月圆之夜,这种夜间出没的啮齿动物会小心地呆在它的洞里。