How to say grandparents (as in the collective group) rather than the specific individual? I feel like there must be an answer to this question. I know each of the individual titles 


  外公，外婆，爷爷，奶奶


but I can't seem to find how to say a collective title 'grandparents' as we would use in English, nor will my dictionary turn up a good answer. 

Can anyone tell me if there is a proper way to say grandparents in Chinese?
祖父母


  祖父母是指父亲的父母亲，又称“爷爷、嫲嫲”、“爷爷、奶奶”。母亲的父母称为外祖父母，在中国南方称为外公、外婆，在中国北方则称为姥姥（或姥娘）、姥爷。自己则分别是祖父母和外祖父母的孙儿或孙女、外孙或外孙女。


It also links to the English page for Grandparent.



National Grandparents Day is also translated as:


  祖父母节