What is the difference of 年纪， 年龄， 岁数 and 岁？

年纪 (niánjì): This term generally refers to someone's age in a more general sense or the stage of life they are in. It can also imply the social or societal implications of age. For example, when someone asks "你多大年纪？" (nǐ duōdà niánjì?) they are asking "How old are you?" in terms of general age category.


年龄 (niánlíng): This term is similar to 年纪 (niánjì) but tends to be more formal. It's commonly used in official documents, medical contexts, or legal matters. For example, when filling out a form, you might see a question like "请输入您的年龄" (qǐng shūrù nín de niánlíng), which means "Please input your age."


岁数 (suìshù): This term specifically refers to the number of years someone has lived. It's often used in a more casual or colloquial context, such as in everyday conversations. For example, "他的岁数不小了" (tā de suìshù bù xiǎo le) means "He's not young anymore."


岁 (suì): This is the Chinese character for "years of age." It's often used together with a number to indicate a specific age. For example, "他十八岁了" (tā shíbā suì le) means "He is eighteen years old."



In summary, while all of these terms relate to age, 年纪 (niánjì) and 年龄 (niánlíng) are more general and formal, while 岁数 (suìshù) and 岁 (suì) are more casual and specifically refer to the number of years someone has lived.