外号 + Nickname
The word 外号 (wàihào) means "nickname" and is used to refer to an informal name given to someone. It can function as a noun or be used in a structure that states what someone's nickname is, as in 外号小狐狸 (nicknamed Little Fox).
同学们都叫他的外号,没人叫他真名。
tóngxuémen dōu jiào tā de wàihào, méi rén jiào tā zhēn míng.
The classmates all call him by his nickname; nobody calls him by his real name.
她的外号叫小太阳,因为她总是很开心。
tā de wàihào jiào xiǎo tàiyáng, yīnwèi tā zǒngshì hěn kāixīn.
Her nickname is Little Sunshine, because she is always so happy.
别叫我的外号了,我不喜欢那个名字。
bié jiào wǒ de wàihào le, wǒ bù xǐhuān nàge míngzì.
Stop calling me by my nickname; I don't like that name.