/ˈbɜ:θdeɪ ||; ˈbɝθˌde/noun [C] the day in each year which is the same date as the one when you were born 生日；出生的日子: My birthday's on November 15th. 我的生日是11月15日。my eighteenth birthday 我的十八岁生日a birthday present/card/cake 生日礼物／贺卡／蛋糕 An anniversary is not the same as a birthday. It is the day in each year which is the same date as an important past event our wedding anniversary the anniversary of the end of the war. anniversary 和 birthday 不同。前者指的是周年纪念日：our wedding anniversary 我们的结婚周年纪念日 the anniversary of the end of the war 战争结束周年纪念日。 When it is a person's birthday we say Happy Birthday ! If we know the person well we send him/her a special card or present. Your eighteenth birthday is an important occasion when you legally become an adult. 庆祝某人生日时我们说 Happy birthday!。很熟稔的话会送给他 / 她一张贺卡或一份礼物。十八岁生日是一个重要的日子，因为法律上已届成人。