a day when you wear pyjamas at home during the day in order to relax and enjoy yourself We have pyjama days when we do absolutely nothing but hang out together and relax. 睡衣的日子里，我们什么也做不了，只能一起出去放松一下。
- (especially in the US)
a day when children wear pyjamas to school to raise money for charity My daughter's middle school has a pajama day twice a year. 我女儿的中学每年两次睡衣一天。