A desert is a very dry area of land where few plants and animals can live. If you find yourself stranded in the middle of the desert, you'll have no company except for the occasional lizard or scorpion.
Desert comes from the Latin desertus, for abandoned or lying in waste. This can refer to a vast sandy area without vegetation, or any empty, lifeless expanse. As a verb, it means to leave someone or something. A soldier who runs away from the army is called a deserter. Occasionally you'll hear someone say, "He got his just deserts," which doesn't have anything to do with abandonment; it means he got what he deserved.