垂询 is a formal and respectful verb meaning 'to inquire' or 'to ask (a question)', used almost exclusively in written or highly polite spoken contexts—especially in business, official correspondence, or customer service. The character 垂 (chuí) literally means 'to hang down', but here functions as an honorific prefix indicating humility and deference (as if the speaker is lowering themselves to seek guidance). 询 (xún) means 'to inquire' or 'to ask'. Together, 垂询 conveys that the speaker regards the listener’s knowledge or authority as superior and worthy of respect.

This term is never used for casual questions among friends or family. It frequently appears in formal letters, email subject lines ('关于贵公司产品之垂询'), company websites ('欢迎垂询'), or reception signage. It always takes a third-person or second-person subject (e.g., '贵方垂询' or '欢迎您垂询') and does not occur with first-person subjects like '我垂询'—that would be grammatically and pragmatically incorrect.