›a person or thing that is seen as a typical example of something: a poster child for sthHe is the poster child for excessive chief executive compensation.a poster child of sthThe company has been the poster child of denial among those convinced of global warming.
›a child with a particular illness or disability whose picture is on posters to raise money to help children who have the same illness or disability: As a March of Dimes poster child, she was a bright, carefree child who refused to let her disability get in the way of playing like the other kids.