the part of every 24-hour period when it is dark because there is very little light from the sun: It gets cold at night. I slept really badly last night. I spent the night at Ted's. He took the night ferry/train. picture of night Alex Walker/Moment/GettyImages Fewer examples The snow came down during the night. I'm not feeling very alert today - not enough sleep last night! They work during the night and sleep by day. We were woken in the night by the wail of ambulance sirens. Get a good night's sleep and you'll feel better able to cope.