There are different types of cousins in Chinese! How to call your cousin in Chinese? Check it out!

Since Chinese people make much of pecking order (長幼有序)~ 

there are several kinds of "cousins" in Chinese language.

Different kinds of "cousins" show the differences in age and gender.

In Mandarin Chinese~ "a cousin" could be...

táng gē 
堂哥 (male cousin, older than you)

táng dì 
堂弟 (male cousin, younger than you)

táng zǐ 
堂姊 (female cousin, older than you)

táng mèi 
堂妹 (female cousin, younger than you)

if this cousin is a child of your father's brother(s).
In General situation, this cousin and you have the same family name.

OR

biǎo gē 
表哥 (male cousin, older than you)

biǎo dì 
表弟 (male cousin, younger than you)

biǎo zǐ 
表姊 (female cousin, older than you)

biǎo mèi
表妹 (female cousin, younger than you)

if this cousin is a child of your father's sister(s)
or a child of your mother's brother(s) or sister(s).
Generally, this cousin's family name and yours are different.

In summary, 

Tang
"堂" ＋ 哥／弟／姊／妹
is a child of your father's brother(s).
Generally, this cousin and you have the same family name.

Biao
“表” ＋ 哥／弟／姊／妹is a child of your father's sister(s) or a child of your mother's brother(s) or sister(s)Generally, this cousin's family name and yours are different.

Other information:

gē
哥  = older brother

dì
弟  = younger brother

zǐ
姊  = older sister

mèi
妹  = younger sister