‘十岁’ literally means ‘ten years’ and is used exclusively to express a person’s age — specifically, being ten years old. The first character 十 (shí) is the numeral ‘ten’, while 岁 (suì) means ‘year’ in the context of human age, similar to ‘years old’ in English. Unlike general time expressions (e.g., 十年 for ‘ten years’), 岁 always refers to age when paired with numerals and is never used for durations like ‘ten years of study’ or ‘ten years ago’.

This term is commonly used in everyday speech and writing when describing children’s ages — especially in school contexts, medical records, family conversations, or birthday celebrations. It functions as a noun phrase and typically appears after a subject (e.g., 他十岁了 — ‘He is ten years old’) or as a predicate complement. It cannot stand alone as a subject without context (e.g., *十岁很聪明 is incomplete; you need a subject like 他十岁很聪明 or 十岁的孩子很聪明).