How do you say younger brother in chinese?

There are two common ways to say "younger brother" in Chinese:

1. 弟弟 (dìdi) - This is the most common and general term for younger brother. It can be used for a biological brother or a brother-like figure.

2. 兄 (xiōng) - This is more formal and literary, and is usually used when referring to a younger brother in a respectful context.

Here's an example of how to use each:

* 我弟弟是一个医生。 (Wǒ dìdi shì yī gè yīshēng.) - My younger brother is a doctor.

* 我的兄长很聪明。 (Wǒ de xiōng zhǎng hěn cōngming.) - My younger brother is very intelligent.

You can also use 小弟弟 (xiǎo dìdi) to be more informal and emphasize the "younger" aspect, especially when talking to children or someone you know well.