Late-night is a term usually used to refer to events or activities that happen during or after midnight. However, if you're looking to add some variety to your vocabulary, there are several synonym options available. For instance, if you're describing something happening during the dark hours, you might use "midnight" or "after-hours" as alternatives to late-night. "Nocturnal" is also an option, though it may be a bit more poetic or dramatic. Additionally, "late evening" or "late at night" can work well if you're trying to specify a particular time frame. No matter which synonym you choose, using varied language can help keep your writing fresh and engaging.