妹妹

妹妹 (mèi mèi) is a term used to refer to one's younger sister. It is a common and affectionate way to address or speak about a younger female sibling, emphasizing familial relationship and closeness.

The character 妹 (mèi) means 'younger sister' and is repeated in the word to emphasize the relationship. The repetition of the same character is a common feature in Chinese to express intimacy or familiarity, similar to how English might use 'sister-sister' for emphasis or affection.

In daily conversation, 妹妹 is often used by older siblings to address their younger sisters, and it can also be used by others when referring to someone else's younger sister. It carries a warm, familiar tone and is commonly used in both formal and informal contexts.