The highest mountain on Earth has several names, and the one most people know, Everest, comes from a man who never saw it.
Quick answer: the British Great Trigonometric Survey of India first called the mountain Peak XV. In 1865, the Royal Geographical Society adopted the name Mount Everest, after Sir George Everest, a former Surveyor General of India. In Nepal it is called Sagarmatha, and in Tibet Chomolungma, often translated as "Goddess Mother of the World".
Peak XV
In the 1850s, surveyors measuring the Himalaya from the plains of India realised that Peak XV was the highest mountain in the world. Its first published height, in 1856, was 29,002 ft (about 8,840 m).
Mount Everest
The Surveyor General, Andrew Waugh, proposed naming the peak after his predecessor, George Everest, and the name was officially adopted in 1865. Interestingly, George Everest himself had objected, arguing that local names should be used.
Sagarmatha
In Nepali, the mountain is Sagarmatha, often translated as "forehead of the sky". The national park around it is Sagarmatha National Park.
Chomolungma
To Tibetans and Sherpas, it is Chomolungma (or Qomolangma), commonly translated as "Goddess Mother of the World".
How high is it?
In 2020, Nepal and China jointly announced a height of 8,848.86 m. See our news report and Everest facts.