Wiktionary
n. Any of the fourteen independent mountains on Earth, all located in Asia, that extend more than 8,000 metres (26,247 ft) above sea level.
Wikipedia
The eight-thousanders are the 14 independent mountains on Earth that are more than high above sea level. All eight-thousanders are located in the Himalayan and Karakoram mountain ranges in Asia. They are the mountains whose summits are in the death zone.
The first recorded attempt on an eight-thousander was when Albert F. Mummery and J. Norman Collie tried to climb Pakistan's Nanga Parbat in 1895. The attempt was unsuccessful when Mummery and two Gurkhas, Ragobir and Goman Singh, were killed by an avalanche.
The first recorded successful ascent of an eight-thousander was by the French Maurice Herzog and Louis Lachenal, who reached the summit of Annapurna on June 3, 1950.
The first person to climb all 14 eight-thousanders was the Italian Reinhold Messner, who completed this task on October 16, 1986. A year later, in 1987, the Polish Jerzy Kukuczka became the second climber to accomplish this feat. Messner had summitted each of the 14 peaks without the aid of supplemental oxygen. This feat was not repeated until nine years later by the Swiss Erhard Loretan in 1995. Phurba Tashi of Nepal has completed the most climbs of the eight-thousanders, with 30 ascents between 1998 and 2011. Juanito Oiarzabal has completed the second most, with a total of 25 times between 1985 and 2011. The alpinist with the highest number of accomplished winter ascents is the Italian Simone Moro, with four peaks (The K2 has never been summited in the winter).
The first woman who summited all 14 eight-thousanders with no disputed climbing was the Spanish Edurne Pasaban, in 2010. In August 2011, Austrian climber Gerlinde Kaltenbrunner became the first woman to climb the 14 eight-thousanders without the use of supplementary oxygen.
The countries with the highest number of climbers that have climbed all 14 eight-thousanders are Italy and South Korea, with five climbers each, followed by Spain, with four climbers. Kazakhstan and Poland have three climbers each that completed the "Crown of the Himalaya".