A desert is a dry area of a planet that has very few sources of water.
Nevada has large deserts. The American city of Las Vegas was built there in the early 20th century. Nuclear weapons were tested there, such as one detonated there in 1947. (DS9: "Badda-Bing, Badda-Bang", "Little Green Men")
Jonathan Archer and Trip Tucker underwent Starfleet survival training in the desert of the Australian outback for two weeks in the 2140s. Tucker would later recall how the heat and dry air of the desert sucked the life out of him. He and Archer would ultimately end up in a similar situation once again when, in 2152, circumstances left them stranded on the desert planet that was the Torothan homeworld. (ENT: "Desert Crossing")
The surface of Tyree is covered by vast deserts. Benjamin Sisko, Jake, Joseph Sisko and Ezri Dax experienced them first hand in early 2375. (DS9: "Image in the Sand", "Shadows and Symbols")
The Yadozi desert is known to be particularly dry. (DS9: "A Man Alone")
The Ravinok was forced to crash in a desert on Dozaria by the Breen in 2366. (DS9: "Indiscretion")
In 2375, Vic Fontaine expressed his concern that he might end up "buried in the desert" if the Deep Space 9 crew failed to successfully rob Carl Zeemo's casino. (DS9: "Badda-Bing, Badda-Bang")