An Eephus pitch (also spelled Ephus) in baseball is a very low-speed junk pitch. The delivery from the pitcher has very low velocity and usually catches the hitter off-guard. Its invention is attributed to Rip Sewell of the Pittsburgh Pirates in the 1940s, although according to historians John Thorn and John Holway, the first pitcher to throw a big blooper pitch was Bill Phillips, who played in the National League on and off from 1890 through 1903. The practice then lay dormant for nearly 40 years until Sewell resurrected it. According to manager Frankie Frisch, the pitch was named by outfielder Maurice Van Robays. When asked what it meant, Van Robays replied, "'Eephus ain't nothing, and that's a nothing pitch." Although the origin is not known for certain, "Eephus" may come from the Hebrew word (pronounced "EFF-ess"), meaning "nothing". The Eephus pitch is thrown overhand like most pitches, but is characterized by an unusual, high arcing trajectory. The corresponding slow velocity bears more resemblance to a slow-pitch softball delivery than to a traditional baseball pitch. It is considered a trick pitch because, in comparison to normal baseball pitches, which run from 70 to 100 miles per hour (110 to 160 km/h), an Eephus pitch appears to move in slow motion at 55 mph (89 km/h) or less, sometimes into the low-40s mph (66–69 km/h).
Sewell's earliest recorded use of the pitch came in a game against the Boston Braves at Forbes Field in Pittsburgh on June 1, 1943, although as early as the spring training season of 1942 Sewell may have been experimenting with the pitch. Sewell went on to win 20 games with the pitch in 1943.
After appearing in over 300 major-league games, Rip Sewell gave up only one career home run off the Eephus, to Ted Williams in the 1946 All-Star Game. Williams challenged Sewell to throw the Eephus. Sewell obliged, and Williams fouled off the pitch. However, Sewell then announced that he was going to throw the pitch again, and Williams clobbered it for a home run. When describing the mechanics of the pitch and why he was able to succeed where others had failed, Williams remarked "A little girl could hit that pitch, but you had to provide all the power yourself." Years later, however, Williams admitted that he had been running towards the pitcher’s mound as he hit the ball, and photographs reveal that he was in fact a few feet in front of the batter’s box when he made contact. Since under Rule 6.06(a) of the Official Baseball Rules, a batter is out for illegal action when he hits a ball with one or both feet on the ground entirely outside the batter's box, Williams would have been out had it been spotted by the home plate umpire.