Definition

• Since the home team always bats last in a baseball game, a walk-off home run can only be hit by a member of the home team. It can only be called a walk-off if it's hit when the score is either tied or the home team is behind. A walk-off home run that caps a come-from-behind victory is generally thought to be more dramatic and is usually followed by a celebration. That became an issue itself in May of 2010 when Kendry Morales of the Angels hit a grand slam to win a game, then injured himself when mobbed by teammates at home plate. The next game another Angel hit a walk-off homer, but the team limited the party to embraces after he touched the plate.
  
  

Coining of the Phrase

• Hall-of-Fame relief pitcher Dennis Eckersley is credited with coining the phrase "walk-off." According to "San Francisco Chronicle," Eckersley used the phrase in 1988 after giving up a home run to lose a game. In Eckersley's use, it was a negative term meant the pitcher had to walk off a loser. When the term became popular, it was more often used to describe the hitter and the home town fans walking off winners.
  
  

Walk-off Situations

• If the score is tied at the bottom of the ninth (or extra) inning, a solo home run would be sufficient for a walk-off. If the home team is down by a single run, then at least a two-run homer is required. If the home team trails by two runs, a three run home run (a home run hit with two runners on base) is needed. A bases-loaded home run -- or a "grand slam" -- is needed if the home team is down by three runs.
  
  

Widespread use

• Due in no small part to ESPN and its use of the term in highlights shows, by the late 1990s "walk-off home run" was ubiquitous in sports culture. In fact, Gene Collier of the "Pittsburgh Post-Gazette" awarded it a "Trite Trophy" in 2000. The Trite Trophy was given annually to the year's worst sports cliche. Past winners include "It is what it is," "Crunch time," and "Show me the money."
  
  

Walk-off Homers in History

• Walk-off home runs have produced some of the most memorable moments in baseball history. Bobby Thomson's three-run home run, which secured the National League Pennant for the New York Giants in 1951, is known as "The Shot Heard Round The World." In the 1960 World Series, Bill Maseroski of the Pittburgh Pirates hit a home run in the final inning of game seven to beat the New York Yankees. Joe Carter won the World Series for his team, the Toronto Blue Jays, with a walk-off shot in 1993.
  
  The term came into major popularity after these famous game-ending homers, so they are referred to as "walk-offs" only in retrospect.