1. [n]  (baseball) an unofficial title won by a batter who leads the league in hitting average and runs batted in and home runs
2. [n]  (horse racing) a title won by a horse that can win the Kentucky Derby and the Belmont Stakes and the Preakness
3. [adj]  (baseball) unofficial championship title for player who heads the league in batting average and home runs and runs batted in
4. [adj]  (horse racing) of a horse that has won the Kentucky Derby and the Belmont Stakes and the Preakness Stakes races

TRIPLE-CROWN is a 12 letter word that starts with T.