彻夜 means 'all night long' or 'throughout the night' and functions primarily as an adverb describing duration. The character 彻 (chè) conveys thoroughness or completeness — as in 'to penetrate fully' or 'to go to the end' — while 夜 (yè) means 'night'. Together, they emphasize uninterrupted continuity from evening until dawn, suggesting no break or pause during the night. It often implies intensity, effort, or emotional weight — for example, staying awake due to worry, working hard, or being unable to sleep.

This term is common in both written and formal spoken Chinese, appearing in news reports, literature, and everyday descriptions of sustained nighttime activity. It’s more literary than colloquial alternatives like 整晚 (zhěng wǎn), and tends to carry a slightly elevated or emotive tone. It usually modifies verbs (e.g., 工作, 聊天, 哭泣) and appears before them or at the sentence end, but never as a subject or object.