贵 (guì): This character's primary meaning is “expensive” or “valuable.” In this context, it functions as an honorific prefix, elevating the following noun. Think of it as meaning “noble” or “honorable.” It shows you value the other person and their family lineage.
姓 (xìng): This character simply means “surname” or “family name.” It is composed of the radicals for “woman” (女) and “birth” (生), reflecting a historical theory that the earliest family names in China were passed down through the maternal line.
When combined, 贵姓 (guìxìng) literally means “noble surname.” When you ask, “您贵姓?” you are asking, “What is your honorable surname?”
贵姓 is reserved for specific, non-casual situations. Using it incorrectly can make you sound strange or distant.
Formal and Professional Settings: This is the default phrase to use when meeting a new client, a business partner, a professor, a government official, or a customer. It's a sign of professionalism.
Showing Respect to Elders: When meeting an older person for the first time, using 您贵姓? is a mandatory sign of respect.
The Classic Question-Answer Pattern: The most common exchange is:
Question: 请问,您贵姓? (Qǐngwèn, nín guìxìng?) - May I ask, what is your honorable surname?
Answer: 免贵姓王。 (Miǎn guì xìng Wáng.) - My humble surname is Wang. (Literally: “Dispense with the 'honorable', my surname is Wang.”)
While the 免贵 (miǎn guì) response is traditional and very polite, many people in modern China will simply respond with 我姓王 (Wǒ xìng Wáng), which is still polite but slightly less formal.