A person of noble birth. this group of people are born into an elite and noble family. Blue bloods generally reside on the East Coast (New England) and live privileged lifestyles. Many blue bloods attend prestigious boarding/preparatory schools, elite institutions (colleges and universities); summer in expensive vacation communities (i.e. Martha's Vineyard, Long Island, Maine, New Hampshire, etc.), and wear preppy clothes. Blue bloods are usually extremely affluent and tend to not flaunt there money. They come from "old money" and are the opposite of "nouveau riche".
President John F. Kennedy (JFK) is a blue blood.
Henry lives in Greenwich, Connecticut; summers in East Hampton, goes to Phillips Exeter Academy and plans to attend Yale in the fall. He's a blue blood.