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Glossary of baseball (J)




The run the pitcher takes from the mound to first base in order to cover for the first baseman who has just fielded the ball.


A home run or to hit a home run. "Hitting a jack" or "Jacking one out of here".


Half-hearted or lazy effort by a player, i.e. "He jaked that play."


  • To pitch far enough inside that the batter is unable to extend while swinging. "The pitcher jammed the batter". The batter was "handcuffed" or "shackled" by the pitch.
  • When runners are in scoring position with less than two outs and good hitters coming up. "The pitcher is in a jam."
  • "Bases are jammed" means "bases are full". There are runners on 1st, 2nd, and 3rd bases. Sometimes referred to as a "jam sandwich".

janitor throwEdit

When an outfielder, trying to throw out a base runner, spins/falls down to get a strong throw

jelly legsEdit

When a batter has legs made out of jelly (normally an off-speed or curve ball heading at an unusual angle) and departs from a good batting stance. “His curve ball . . . it jelly-legs you.” - Phillies First Baseman Jim Thome, referring to Barry Zito's curve.[1]


To hit the ball hard, typically used to refer to pulling the ball over the fence for a home run. "Lee jerked one of his patented doubles into the left-field corner against Mets lefty Johan Santana."[2]


A Punch and Judy hitter who hits with little power.


  • "Bases juiced" means bases loaded.
  • A player who is said to be juiced is thought to be taking performance-enhancing drugs. "It is now assumed, of course, that Bonds may well have been juiced on steroids at the time; the previous year he had set the all-time single-season record of 73 home runs, and his musculature was almost freakishly swollen."[3]
  • A baseball that is said to be juiced is doctored or manufactured in some way that makes it travel farther when a batter hits it. "Spectacular increases in home runs have often raised the question: Has the ball been juiced up to travel farther, in order to increase the number of home runs?"[4]


  • A fielder is said to get a good jump on the ball when he anticipates or reacts quickly to a batted ball and is thereby able to make a good play by fielding or catching it.[5] Also see crack of the bat.
  • A baserunner gets a good jump when he is able to leave the base well before the pitch reaches the plate. "Upsetting the timing of the baserunner can effectively prevent him from getting a good jump.... Base runners often read a pitcher's look and get their jump, or start, based on the pattern the pitcher establishes."[6]

Junior CircuitEdit

The American League, so-called because it is the younger of the two major leagues. The American League was founded in 1901, while the National League – the Senior Circuit – was founded in 1876.


  • breaking balls and knuckleballs, pitches that are difficult to hit due to movement rather than velocity. The term is also used to describe a "junk pitcher" or a junkball pitcher. "I couldn't believe he threw me a fastball because he had me down 1-2", Thames said. "He's usually a junk pitcher and he tried to sneak a fastball past me, and he left it up."[7] See also: Eephus pitch

junkball pitcherEdit

A pitcher who throws predominantly junk, usually due to a weak (or slow) fastball. A junkballer or a junk artist: "Like all junk artists, Trujillo will have to prove himself at the higher levels before getting a shot at a major league job."[8] See also: Eephus pitch


  1. ^ Barry Zito Quotes
  2. ^ American beauty -
  3. ^ Eugene Robinson, "Fans on the Juice", Washington Post, December 18, 2007.
  4. ^ Thomas Sowell :: :: Was the ball juiced?
  5. ^ See Allan R. Andrews, "A Good Jump on the Ball: Algorithm in the Outfield", The American Reporter (8 October 1998).
  6. ^ Jack Stallings and Bob Bennett, Eds., Baseball Strategies: Your Guide to the Game within the Game, American Baseball Coaches Association, 2003, p. 125.
  7. ^ ESPN - MLB Baseball Teams, Scores, Stats, News, Standings, Rumors - Major League Baseball
  8. ^ John Sickels Baseball Newsletter (June 15, 2001).