Although ambidexterity is rare, ambidextrous people may still gravitate towards performing certain types of tasks with a specific hand. The degree of versatility with each hand is generally the qualitative factor in determining a person's ambidexterity.
In modern times, it is more common to find people considered ambidextrous who were originally left handed, and who learned to be ambidextrous either deliberately or during childhood in institutions such as schools where right-handed habits are often emphasized. Also, since many everyday devices are designed to be only ergonomic for right-handed people, many left-handed people choose to use the device with the right hand (good examples are can openers or scissors). As a result, left-handed people are much more likely to develop motor skills in their non-dominant hand than right-handed people (who are not subjected to left-favouring devices). Ambidexterity is often encouraged in activities requiring a great deal of skill in both hands, such as juggling, swimming, percussion or keyboard music, word processing, surgery, body boxing, and combat.
The word "ambidextrous" is derived from the Latin roots ambi, meaning "both," and dexter, meaning "right" or favorable. Thus, "ambidextrous" is literally "right on both sides". The term ambidexter in English was originally used in a legal sense of jurors who accepted bribes from both parties for their verdict. Jurors found guilty of such bribery had to forfeit decies tantum, ten times as much as they received.
Ambidexterity is highly prized in the sport of baseball. "Switch hitting" is the most common phenomenon, and is highly prized because a batter usually has a higher statistical chance of successfully hitting the baseball when it is thrown by an opposite handed pitcher. Therefore, an ambidextrous hitter can bat from whichever side is most advantageous to him or her in that situation. Pete Rose, who had more hits than anyone else in the history of Major League Baseball was a "switch hitter.
Ambidextrous pitchers have also been known. Tony Mullane won 284 games in the 19th century, and also Elton Chamberlain in 1888 and Larry Corcoran in 1884. Greg A. Harris is the only major league pitcher in the modern era to pitch with both his left and his right arm. A natural right-hander, by 1986 he could throw well enough with his left hand that he felt capable of pitching with either hand in a game. Harris wasn't allowed to throw left-handed in a regular-season game until September 28, 1995, the next-to-last game of his career. Against the Cincinnati Reds in the ninth inning, Harris (then a member of the Montreal Expos) retired Reggie Sanders pitching right-handed, then switched to his left hand for the next two hitters, Hal Morris and Ed Taubensee, who both batted left-handed. Harris walked Morris but got Taubensee to ground out. He then went back to his right hand to retire Bret Boone to end the inning. One Division I NCAA pitcher, Pat Venditte formally of the Creighton Bluejays, now with the New York Yankees Staten Island Class A team, regularly pitches with both arms. Venditte won his first game as a professional on June 28th, striking out batters with both left and right-handed pitches. Venditte is consulting with ambidextrous guru Michael J. Lavery, the Co-Founder of Whole Brain Planet, Inc. in an effort to improve not only his power but his ball control from the mound. Lavery is also working with Chuck Mellick, a Tracy, California semi-pro pitcher to help him accomplish his goal to set a Guinness World Record to be the first person to pitch over 90 miles-an-hour accurately with both arms. Lavery is also working with High School pitcher Matthew Berish and little leaguer Nick Bohannan.
Billy Wagner was a natural right-handed pitcher in his youth, but after breaking his throwing arm twice, he taught himself how to use his left arm by throwing nothing but fastballs against a barn wall. He became a dominant left-handed relief pitcher, most known for his 100+ MPH fastball. In his 1999 season, Wagner captured the National League Relief Man of the Year Award as a Houston Astro.
In pool and snooker, a player can reach farther across the table if they are able to play with either hand, since the cue must either be placed on the left or the right side of the body. Snooker player Ronnie O'Sullivan is unique amongst the current ranks of top snooker professionals, in that he is able to play to world standard with his left hand. While he lacks power in his left arm, his ability to alternate hands allows him to take shots that would otherwise require awkward cueing. When he first displayed this ability in the 1996 World Championship against Alain Robidoux, the Canadian accused him of disrespect. O'Sullivan responded that he played better with his left hand than Robidoux could with his right. O'Sullivan was summoned to a disciplinary hearing in response to Robidoux's formal complaint, where he had to prove that he could play to a high level with his left hand. He played three frames of snooker against former world championship runner-up Rex Williams, winning all three. The charge of bringing the game into disrepute was subsequently dropped.
Other sports in which a degree of cross-dominance can be useful include skateboarding, where trick execution from the switch-stance is acclaimed for its high degree of difficulty, basketball, where the player may choose to make a pass or shot with the weaker hand; hockey and ice hockey, where a player may shoot from the left or right-side of the body; and combat sports where the fighter may choose to face their opponent with either the left shoulder forward in a right-handed stance or the right shoulder forward in a left-handed stance. Ice hockey player Gordie Howe used a hockey stick with an uncurved blade, so he could use either hand.
In figure skating, most skaters who are right-handed spin and jump to the left, and vice versa for left-handed individuals. Olympic Champion figure skater John Curry notably performed his jumps in one direction while spinning predominantly in the other. Very few skaters have such an ability to perform jumps and spins in both directions, and it is now considered a "difficult variation" in spins under the ISU Judging System to rotate in the non-dominant direction. Michelle Kwan used an opposite-rotating camel spin in some of her programs as a signature move. No point bonus exists for opposite direction jumps or bi-directional combination jumps despite their being much harder to perfect.
In skateboarding, it's highly advantageous if a skater can skate successfully with not only their dominant foot but also the less dominant. Hence the term "switch skating". Dominant switch skateboarders include Eric Koston, Paul Rodriguez, Drew Cecil, and Bob Burnquist.
It is much the same situation in surfing. Surfers who ride equally well in either stance are said to be surfing "switch-foot."
Some players find cross-dominance advantageous in golf, especially if a left-handed player utilizes right-handed clubs. Having more precise coordination with the left hand is believed to allow better-controlled, and stronger drives.
In golf, Mac O'Grady was a touring pro who played right-handed, yet could play "scratch" (no handicap) golf left-handed. He lobbied the USGA for years to be certified as an amateur "lefty" and a pro "righty" to no avail.
In athletics, Jonathan Edwards, a now-retired British triple jumper who still holds the world record in that event, was known to be able to kick with either foot while he played rugby. He displayed unprecedented ambidexterity while jumping off either foot during his competitive jumps.
In soccer, being able to kick with both feet provides more options for both passing and scoring, as well as the ability to play up both wings. Therefore, players with the ability to use their weaker foot with proficiency are valuable in any team.
Michael Beasley, one of the top collegiate basketball players is ambidextrous.
In American football, it is especially advantageous to be able to use both arms. Ambidextrous receivers can make one-handed catches with both hands, quarterbacks can roll out of the pocket and throw with either arm, confusing the defense, lineman can have their shoulders square and produce an equal amount of power with both arms, and punters can handle a bad snap and roll out and punt with either leg, limiting the chance of a block.
Receivers and corners can play on both the strong and weak sides equally if they do not have a preference.
With respect to tools, ambidextrous may be used to mean that the tool may be used equally well with either hand, as in "ambidextrous knife" referring to the opening mechanism on a folding knife, or can be interchanged between left and right in some other way, such as an "ambidextrous headset" which can be worn on either the left or right ear. Such devices may not be formally achiral, but interchangeable between different modes.