趁机 (chèn jī) is a verb meaning 'to seize the opportunity' or 'to take advantage of a favorable moment.' It combines 趁 (chèn), which means 'to take advantage of' or 'to use an occasion,' and 机 (jī), meaning 'opportunity' or 'chance.' Together, they convey the idea of acting promptly when conditions are right — not in a negative sense like 'exploiting,' but rather in a neutral or positive way, such as making timely progress or solving a problem efficiently.

This expression is commonly used in everyday spoken and written Chinese, especially when describing actions taken during brief windows of opportunity — for example, during a lull in a meeting, while someone is distracted, or when resources become temporarily available. It often implies alertness, quick thinking, and initiative. While it can occasionally carry a slightly opportunistic nuance depending on context, it’s generally neutral and widely accepted in both formal and informal registers.