爸爸,妈妈 no need to explain 弟弟 younger brother 哥哥 older brother 妹妹 younger sister 姐姐 older sister 叔叔 father's younger brother 婶婶 father's younger brother's wife 伯伯/伯父 father's older brother 伯母 father's older brother‘s wife 姑姑 father's sister 姑父 father's sister's hudsband 姨妈 mother's sister 姨夫 mother's sister's hudsband 舅舅 mother's brother 舅妈 mother's brother's wife 爷爷 grandpa from father side 奶奶 grandma from father side 姥姥/外婆 grandpa from mother side 老爷/外公 grandma from mother side I got bored from just typing them...If you ever marry into a Chinese family, you don't want to mess them.

Acutally, in English they are all "uncles" which means "叔叔"。 But in China, people call father's elder brother as "伯父"， younger brother“叔叔”. And "姨丈"means your mother's sisters's husband.We also call strangers whose age is similar to your father as"叔叔". But we cannot call "伯父，叔叔，姨丈" as "叔叔"。

叔叔generally means your father‘s younger brother In some traditional family that may be regarded as impoliteness. If you should go with your parents you could ask them to remind you in time.