Vocabulary: All About Kids

Kid is an informal word which means a child.
I’m taking the kids (= my children) to the zoo this afternoon.
Kid also refers to a young person.
college kids
Those soldiers are just kids.
In American English, kid also means younger (of a brother or sister).
his kid sister
Kiddie is an informal word to refer to a small child:
I carry my little boy in a kiddie seat on the back of my bike.
Kiddo (especially in American spoken English) is a way of addressing someone you know, usually a young person:
Come on kiddo, let’s go.
Kid’s stuff (in American English) means something that is suitbale only for children, because it is too simple, unsophisticated or boring.
The exam as kid’s stuff compared to the one we had last year.