grandson      
noun [ C ] uk/ˈɡræn.sʌn/ us/ˈɡræn.sʌn/
A2 孙子;外孙
the son of a your son or daughter
 - More examples
 - We've got a new grandson.
 - We have three granddaughters and a grandson.
 - Our grandson is coming to stay for the weekend.
 - Our grandson will be four next week.
 - We have six grandsons but no granddaughters.