趁便 (chèn biàn) is an adverb meaning 'while at it' or 'while convenient,' expressing the idea of doing something extra or incidental during an opportunity that already exists. The character 趁 (chèn) means 'to take advantage of' or 'to seize,' while 便 (biàn) means 'convenience' or 'opportunity.' Together, they convey the notion of capitalizing on a favorable moment to handle another small task without making a special effort.

This expression is commonly used in spoken and written Chinese for polite, efficient communication—especially when suggesting or acknowledging that someone is handling multiple matters in one trip or action. It often appears in casual conversation, emails, or instructions where efficiency and consideration are valued. While not formal in tone, it’s neutral and widely appropriate across most everyday contexts, such as running errands, sending messages, or completing related tasks.