碰巧 is an adverb meaning 'by coincidence' or 'as it happens' — it describes an unplanned, fortuitous occurrence where two events align unexpectedly. The character 碰 (pèng) literally means 'to bump into' or 'to encounter', while 巧 (qiǎo) means 'clever', 'apt', or 'fortunate'. Together, they evoke the idea of 'bumping into good fortune' — a chance meeting or timely alignment that feels serendipitous rather than intentional.

This word is commonly used in spoken and written Chinese to soften statements about coincidental timing or unexpected overlap — for example, meeting someone you weren’t planning to see, or discovering something useful just when you needed it. It carries a neutral-to-positive tone and often implies pleasant surprise. Unlike formal equivalents like 恰好 (qiàhǎo), 碰巧 sounds more conversational and natural in everyday storytelling or casual explanations.