In baseball or softball, a strikeout (or strike-out) occurs when a batter racks up three strikes during a time at bat. It usually means the batter is out. A strikeout is a statistic recorded for both pitchers and batters, and is denoted by K. A strikeout looking is denoted by a ꓘ. 
Although a strikeout suggests that the pitcher dominated the batter, the free-swinging style that generates home runs also leaves batters susceptible to striking out. Some of the greatest home run hitters of all time — such as Alex Rodriguez, Reggie Jackson, and Sammy Sosa — were notorious for striking out.
A pitched ball is ruled a ball by the umpire if the batter did not swing at it and, in that umpire's judgement, it does not pass through the strike zone. Any pitch at which the batter swings unsuccessfully or, that in that umpire's judgement passes through the strike zone, is ruled a strike. Each ball and strike affects the count, which is incremented for each pitched ball with the exception of a foul ball on any count with two strikes. That is, a third strike may only occur by the batter swinging and missing at a pitched ball, or the pitched ball being ruled a strike by the umpire with no swing by the batter. A pitched ball that is struck by the batter with the bat on any count, and is not a foul ball or foul tip, is in play. A batter may also strike out by bunting, even if the ball is hit into foul territory.
A pitcher receives credit for (and a batter is charged with) a strikeout on any third strike, but a batter is out only if one of the following is true:
- The third strike is pitched and caught in flight by the catcher (including foul tips);
- On any third strike, if a baserunner is on first and there are zero or one outs;
- The third strike is bunted foul and is not caught by a fielder.
Thus, it is possible for a batter to strike out, but still become a runner and reach base safely if the catcher is unable to catch the third strike cleanly, and he then does not either tag out the batter or force him out at first base. In Japan, this is called furinige (振り逃げ), or "swing and escape". In Major League Baseball, it is known as an uncaught third strike. When this happens, a strikeout is recorded for both the pitcher and the batter, but no out is recorded. Because of this, a pitcher may occasionally be able to record more than three strikeouts in one half-inning.
It is also possible for a strikeout to result in a fielder's choice. With the bases loaded and two strikes with two outs, the catcher drops the ball or catches it on the bounce. The batter-runner is obliged to run for first base and other base-runners are obliged to attempt to advance one base. Should the catcher field the ball and step on home plate before the runner from third base can score, then the runner from third base is forced out.
In baseball scorekeeping, a swinging strikeout is recorded as a K, or a K-S. A strikeout looking (where the batter does not swing at a pitch that the umpire then calls strike three) is often scored with a backward K, and sometimes as a K-L, CK, or Kc (the 'c' for 'called' strike). Despite the scorekeeping custom of using "K" for strikeout, "SO" is the official abbreviation used by Major League Baseball.
"K" is still commonly used by fans and enthusiasts for purposes other than official record-keeping. One baseball ritual involves fans attaching a succession of small "K" signs to the nearest railing, one added for every strikeout notched by the home team's pitcher, following a tradition started by New York Mets fans in honor of "Dr. K", Dwight Gooden. The "K" may be placed backward in cases where the batter strikes out looking, just as it would appear on a scorecard. Virtually every televised display of a high-strikeout major league game will include a shot of a fan's strikeout display, and if the pitcher continues to strike out batters, the display may be shown following every strikeout.
The use of "K" for a strikeout was invented by Henry Chadwick, a newspaper journalist who is widely credited as the originator of the box score and the baseball scorecard. As is true in much of baseball, both the box score and scorecard remain largely unchanged to this day. Chadwick decided to use "K", the last letter in "struck", since the letter "S" was used for "sacrifice." Chadwick was responsible for several other scorekeeping conventions, including the use of numbers to designate player positions.
Those unaware of Chadwick's contributions have speculated that "K" was derived from the last name of 19th century pitcher Matt Kilroy. If not for the evidence supporting Chadwick's earlier use of "K", this explanation would be reasonable. Kilroy raised the prominence of the strikeout, setting an all-time single-season record of 513 strikeouts in 1886, only two years after overhand pitching was permitted. His record, however, is limited to its era since the pitcher's mound was only 50 feet (15 m) from the batter during that season. It was moved to its current distance of 60'6" in 1893. The modern record (1901–present) is 383 strikeouts, held by Nolan Ryan, one better than Sandy Koufax's 382.
For 55 years, Walter Johnson held the career strikeout record, at 3,508. That record fell in 1982 to Nolan Ryan, who was then passed by Steve Carlton, before Ryan took the career strikeout record for good at 5,714.
Early rules stated that "three balls being struck at and missed and the last one caught, is a hand-out; if not caught is considered fair, and the striker bound to run." The modern rule has changed very little. The addition of the called strike came in 1858.
In 1880, the rules were changed to specify that a third strike had to be caught on the fly. A later adjustment to the dropped third strike rule specified that a batter is automatically out when there are fewer than two out and a runner on first base. In 1887, the number of strikes for an out was changed to four, but it was promptly changed back to three the next season.
Jargon and slang
A swinging strikeout is often called a whiff, while a batter who is struck out by a fastball is often said to have been blown away. A batter who strikes out on a swung third strike is said to have fanned (as in a fanning motion), whereas if he takes a called third strike it is called a punchout (describing the plate umpire's dramatic punching motion on a called third strike). However, sometimes these words are used as general synonyms for a strikeout, irrespective of whether it was swinging or looking. The announcer Ernie Harwell called a batter who took a called third strike, usually on the other team, "out for excessive window-shopping" or having "stood like the house by the side of the road".
On a called third strike, it is said that the batter was caught looking, or that he looked at a strike. Typically, a called third strike can be somewhat more embarrassing for a batter, as it shows that he was either fooled by the pitcher or, even worse, had a moment of hesitation.
For example, Carlos Beltrán was caught looking at strike 3 to end the 2006 NLCS, and the season, for the New York Mets. Sports commentators have also been known to refer to it as browsing if the batter did not move his bat at all.
A pitcher is said to strike out the side when he retires all three batters in a half-inning by striking them out. This term is also used when all three outs were caused by strike outs, regardless of how other batters in the inning fared. If a pitcher strikes out three batters on nine pitches, he is said to have pitched an immaculate inning. A batter that takes the third strike looking, especially on a breaking pitch like a slider or a curveball that appears to be out of the strike zone but drops in before he can get the bat off his shoulders, can be said to have been frozen.
In slang, when a batter strikes out three times in a game, he is said to have completed a hat trick. If he strikes out four times, it is called a golden sombrero. He receives a platinum sombrero if he strikes out five times, and this dishonor is also known as the Olympic Rings.
Striking out six times is a rare occurrence, which in the history of major league play has only occurred in games that went to extra innings, with Sam Horn of the Baltimore Orioles being one of the few to do this. The slugger's then-teammate, pitcher Mike Flanagan, told reporters after that 1991 event that six strikeouts would thereafter be known as a Horn. He added that if anyone ever strikes out seven times in one game, it will be a Horn of Plenty.
Some pitchers who specialize in strikeouts have acquired nicknames including the letter "K." Dwight Gooden was known as "Doctor K" (back-referencing basketball star Julius Erving a.k.a. "Dr. J"). Francisco Rodríguez is known as "K-Rod." Roger Clemens has taken the "K" name to an extreme by naming his four sons Koby, Kory, Kacy, and Kody. Tim Lincecum is nicknamed "The Say 'K' Kid", referencing former Giants player Willie Mays who was called "The Say Hey Kid." Daisuke Matsuzaka is known as "Dice-K", a term which was used as a pronunciation guide for his name when he first arrived in MLB.
Hall of Fame strikeout artist Sandy Koufax of the Los Angeles Dodgers coincidentally has a last name starting with "K", and in his call of the pitcher's perfect game in 1965, Dodgers announcer Vin Scully commented that Koufax's name "will always remind you of strikeouts".
More than three strikeouts in an inning
If a third strike is not caught cleanly by the catcher, it is still recorded as a strikeout for both the pitcher and the batter, but the batter is not out but becomes a runner, and the play is still alive. (This is not true when first base is occupied and there are fewer than two outs; see Uncaught third strike.) The batter-runner may occupy first base unless the defense tags him out or throws him out. Therefore, a pitcher can achieve more than three strikeouts in one standard half-inning.
Prior to 1960, the event occurred only eight times. The first Major League player to be credited with the feat was Ed "Cannonball" Crane of the New York Giants on October 4, 1888. It has occurred in Major League Baseball 76 times. Chuck Finley accomplished the feat on May 12 and August 15, 1999, with the Anaheim Angels and again on April 16, 2000, with the Cleveland Indians. Pete Richert of the Los Angeles Dodgers is the only pitcher to do it in his MLB debut (April 12, 1962, against the Cincinnati Reds). Steve Delabar struck out 4 men in the 10th inning, and recorded the win in a 3-2 victory over the Chicago White Sox on August 13, 2012, making him the first pitcher in major league history to record four strikeouts in an extra inning.
For a list of pitchers who have achieved more than three strikeouts in an inning, including the most recent pitcher to do so, see List of Major League Baseball single-inning strikeout leaders.
Five strikeouts in one inning has never occurred in a regulation Major League Baseball game. It has occurred at least three times at the minor league level. Mike Schultz of the Lancaster JetHawks struck out five batters in one inning on July 16, 2004, and Garrett Bauer of the Rockford RiverHawks struck out five batters in one inning on July 1, 2008. That such has never happened in Major League play reflects the rarity of a pitcher that has gotten a strikeout with an uncaught third strike, but also that,
(1) a second uncaught third strike happens with two outs, whether or not a runner is on first base and that the batter safely reaches first base, or
(2) that with fewer than two outs, the first baserunner, that reached base on an uncaught third strike, must have scored or be on a base other than first, before another strikeout with a dropped 3rd strike can occur. Alternately, One or two normal strikeouts must be recorded before the second runner can possibly reach firstbase off a dropped 3rd strike; only when the second batter-runner reaches base, can the 5th strikeout be completed.
Houston Astros pitcher Joe Niekro struck out five Minnesota Twins batters in the first inning of an exhibition spring training game, April 7, 1976 at New Orleans. Niekro's catcher, Cliff Johnson, was charged with five passed balls in the inning. Exhibition games are not recorded in official statistics.
- Nolan Ryan – 5,714
- Randy Johnson – 4,875
- Roger Clemens – 4,672
- Steve Carlton – 4,136
- Bert Blyleven – 3,701
- Tom Seaver – 3,640
- Don Sutton – 3,574
- Gaylord Perry – 3,534
- Walter Johnson – 3,509
- Greg Maddux – 3,371
- Phil Niekro – 3,342
- Ferguson Jenkins – 3,192
- Pedro Martínez – 3,154
- Bob Gibson – 3,117
- Curt Schilling – 3,116
- John Smoltz – 3,084
- CC Sabathia – 2,931
- Jim Bunning – 2,855
- Mickey Lolich – 2,832
- Mike Mussina – 2,813
- CC Sabathia – 2,931
- Justin Verlander – 2,509
- Bartolo Colón – 2,490
- Félix Hernández – 2,391
- Zack Greinke – 2,303
- John Lackey – 2,294
- Cole Hamels – 2,291
- Max Scherzer – 2,253
- Clayton Kershaw – 2,168
- James Shields – 2,121
- Jon Lester – 2,089
- Randy Johnson – 10.61
- Chris Sale – 10.55
- Stephen Strasburg – 10.54
- Kerry Wood – 10.32
- Max Scherzer – 10.20
- Pedro Martínez – 10.04
- Corey Kluber – 9.91
- Clayton Kershaw – 9.86
- Nolan Ryan – 9.55
- Óliver Pérez – 9.45
- Randy Johnson, 2001 – 13.41
- Pedro Martínez, 1999 – 13.20
- Chris Sale, 2017 – 12.93
- Kerry Wood, 1998 – 12.58
- Randy Johnson, 2000 – 12.56
|Nolan Ryan||383||1973||California Angels||AL||8|
|Sandy Koufax||382||1965||Los Angeles Dodgers||NL||9|
|Randy Johnson||372||2001||Arizona Diamondbacks||NL||11|
|Nolan Ryan||367||1974||California Angels||AL||14|
|Randy Johnson||364||1999||Arizona Diamondbacks||NL||15|
|Rube Waddell||349||1904||Philadelphia Athletics||AL||18|
|Bob Feller||348||1946||Cleveland Indians||AL||19|
|Randy Johnson||347||2000||Arizona Diamondbacks||NL||20|
|Nolan Ryan||341||1977||California Angels||AL||25|
|Randy Johnson||334||2002||Arizona Diamondbacks||NL||30|
|Matt Kilroy||513||1886||Baltimore Orioles||AA||1|
|Toad Ramsey||499||1886||Louisville Colonels||AA||2|
|Hugh Daily||483||1884||Chicago Browns/Pittsburgh Stogies/Washington Nationals||UA||3|
|Dupee Shaw||451||1884||Detroit Wolverines/Boston Reds||NL/UA||4|
|Old Hoss Radbourn||441||1884||Providence Grays||NL||5|
|Charlie Buffington||417||1884||Boston Beaneaters||Da||6|
|Guy Hecker||385||1884||Louisville Eclipse||AA||7|
|Nolan Ryan||383||1973||California Angels||AL||8|
|Sandy Koufax||382||1965||Los Angeles Dodgers||NL||9|
|Bill Sweeney||374||1884||Baltimore Monumentals||UA||10|
Progression of major league strikeout record for one nine-inning game, regular season (partial listing):
- 18 – Dupee Shaw, Boston Reds (UA), July 19, 1884. Matched by:
- 16 – Rube Waddell, July 29, 1908
- 18 – Bob Feller, October 2, 1938. Matched by:
- 19 – Steve Carlton, September 15, 1969. Matched by:
- 20 – Roger Clemens, April 29, 1986. Matched by:
- 21 – Boston Red Sox (five pitchers), September 25, 2016 (the first nine innings of an extra-inning game)
Progression of strikeout record for one game, World Series:
- 10 – 1903 (first modern Series), Game 1, Deacon Phillippe
- 11 – 1903, Game 2, Bill Dinneen
- 12 – 1906, Game 3, Ed Walsh
- 13 – 1929, Game 1, Howard Ehmke
- 14 – 1953, Game 3, Carl Erskine
- 15 – 1963, Game 1, Sandy Koufax
- 17 – 1968, Game 1, Bob Gibson
Progression of major league strikeout record for a relief pitcher, regular season (partial listing):
The top 15 Major League Baseball career strikeout leaders (as of completion of the 2017 Major League Baseball season):
- Reggie Jackson – 2,597
- Jim Thome – 2,548
- Adam Dunn – 2,379
- Sammy Sosa – 2,306
- Alex Rodriguez – 2,287
- Andrés Galarraga – 2,003
- José Canseco – 1,942
- Willie Stargell – 1,936
- Mike Cameron – 1,901
- Mike Schmidt – 1,883
- Fred McGriff – 1,882
- Tony Pérez – 1,867
- Ryan Howard – 1,843
- Bobby Abreu – 1,840
- Derek Jeter – 1,840
Active batters with over 1,400 K's (as of completion of the 2017 Major League Baseball season):
- Ryan Howard – 1,843
- Mark Reynolds – 1,806
- Carlos Beltrán – 1,795
- Curtis Granderson 1,712
- Adrián Beltré – 1,636
- Miguel Cabrera – 1,626
- Melvin Upton Jr. – 1,561
- Justin Upton – 1,544
- Chris Davis – 1,504
- Mike Napoli – 1,468
- Matt Kemp – 1,466
- Jhonny Peralta – 1,450
- Jayson Werth – 1,450
Single season strikeout records (batters):
|Mark Reynolds||Arizona Diamondbacks||223||2009|
|Adam Dunn||Chicago White Sox||222||2012|
|Chris Davis||Baltimore Orioles||219||2016|
|Chris Carter||Houston Astros||212||2013|
|Mark Reynolds||Arizona Diamondbacks||211||2010|
|Chris Davis||Baltimore Orioles||208||2015|
|Aaron Judge||New York Yankees||208||2017|
|Chris Carter||Milwaukee Brewers||206||2016|
|Drew Stubbs||Cincinnati Reds||205||2011|
|Mark Reynolds||Arizona Diamondbacks||204||2008|
Progression of record for total strikeouts by both teams in one game (partial listing):
- 33 – San Francisco Giants at Philadelphia Phillies (14 innings), June 22, 1958. Matched by:
- 36 – San Francisco Giants at New York Mets (23 innings), May 31, 1964
- 43 – California Angels at Oakland Athletics (20 innings), July 9, 1971
- 48 – New York Yankees at Chicago Cubs (18 innings), May 7, 2017
- 3,000 strikeout club
- Baseball statistics
- List of Major League Baseball annual strikeout leaders
- List of Major League Baseball single-game strikeout leaders
- List of Major League Baseball pitchers who have struck out three batters on nine pitches
- List of Major League Baseball career strikeout leaders
- Major League Baseball (2001–2009). "Baseball Basics: Abbreviations". Retrieved September 2, 2009.
- "The Official Site of Major League Baseball: Official info: Baseball Basics: Abbreviations". Mlb.mlb.com. May 24, 2013. Retrieved June 6, 2013.
- "In baseball scoring, why is a strikeout marked with a K?". Thestraightdope.com. Retrieved December 20, 2005.
- "Truth&Rumors | K-Rod expects to leave Angels". FanNation. March 22, 2008. Retrieved June 6, 2013.
- Shaikin, Bill (September 25, 2016). "Three calls that are arguably Vin Scully's all-time best". Los Angeles Times. Retrieved December 26, 2017.
- Official Rules of Major League Baseball 6.09b
- "Four Strikeouts in One Inning". Baseball-almanac.com. 2011. Retrieved May 12, 2011.
- "Fluke or Feat: Ranking the Toughest Single Game Accomplishments in MLB". Bleacherreport.com. 2011. Retrieved May 13, 2011.
- "Rare Feats: Four K's in One Inning". mlb.mlb.com. Retrieved August 17, 2012.
- Kercheval, Nancy. "Burnett Becomes First New York Yankee to Strike Out 4 in a Single Inning". Bloomberg. Retrieved September 28, 2011.
- "Los Angeles Dodgers 11, Cincinnati Reds 7". Retrosheet.org. April 12, 1962. Retrieved October 17, 2010.
- "Cooper drives in winning run as Jays beat White Sox in 11th". TSN.ca. August 13, 2012. Retrieved August 14, 2012.
- "Bauer K's 5 in first; James hits winner in 12th". Rockfordriverhawks.com. July 1, 2008. Retrieved October 17, 2010.
- Schlossberg, Dan (2007). Baseball Gold: Mining Nuggets from Our National Pastime. Chicago: Triumph Books. pp. 302–303. ISBN 978-1-57243-958-0.
- The Chicago Tribune, April 8, 1976, p. C2
- "Career Leaders & Records for Strikeouts". Baseball-Reference.com. Retrieved October 3, 2017.
- "Active Leaders & Records for Strikeouts". Baseball-Reference.com. Retrieved October 3, 2017.
- "Career Leaders & Records for Strikeouts per 9 IP". Baseball-Reference.com. Retrieved October 3, 2017.
- "Single-Season Leaders & Records for Strikeouts per 9 IP". Baseball-Reference.com. Retrieved October 3, 2017.
- "Strikeouts Single Season Leaders by Baseball Almanac". Baseball-almanac.com. Retrieved June 6, 2013.
- "Single-Season Leaders & Records for Strikeouts".
- "Baseball Recordbook 2007" (PDF). Sporting News. p. 63.
- Bevis, Charlie. "George Bignell". SABR. Retrieved June 6, 2013.
- "Boston Red Sox 3, Tampa Bay Rays 2". Retrosheet. September 25, 2016. Retrieved May 8, 2017.
- "Washington Senators 2, Baltimore Orioles 1". Retrosheet. September 12, 1962. Retrieved May 8, 2017.
- "St. Louis Cardinals 4, Detroit Tigers 0". Retrosheet. October 2, 1968. Retrieved May 8, 2017.
- "Strikeout Records". Baseball Almanac.
- "Arizona Diamondbacks 3, San Diego Padres 0". Retrosheet. July 18, 2001. Retrieved May 8, 2017.
- "San Francisco Giants 5, Philadelphia Phillies 4 (1)". Retrosheet. June 22, 1958. Retrieved May 8, 2017.
- "Major League Records Set in Marathon". Chicago Tribune. June 1, 1964. Retrieved May 8, 2017 – via newspapers.com.
- "Cleveland Indians 3, Washington Senators 2 (2)". Retrosheet. June 14, 1963. Retrieved May 8, 2017.
- "San Francisco Giants 8, New York Mets 6 (2)". Retrosheet. May 31, 1964. Retrieved May 8, 2017.
- "Mangual Ends Angels' Night Life". St. Louis Post-Dispatch. July 10, 1971. Retrieved May 8, 2017 – via newspapers.com.
- "Oakland Athletics 1, California Angels 0". Retrosheet. July 9, 1971. Retrieved May 8, 2017.
- "Yankees-Cubs sets MLB record with 48 combined strikeouts". ESPN.com. May 8, 2017. Retrieved May 8, 2017.
- "New York Yankees vs. Chicago Cubs - Box Score - May 07, 2017". ESPN.com. May 7, 2017. Retrieved May 8, 2017.