Etymology is, of course, the study of the origin of words and how the meaning of words has changed over the course of history. Here's how the word whiskey evolved.
Medieval monks called it aqua vitae, meaning “life water.” The expression was transformed into uisce beatha when it was transferred to Gaelic. As time passed and the word was anglicized, uisce evolved into uige, usque, and then uisky, which bears an obvious and close resemblance to “whiskey.”
You may have noticed that you can spell the drink two different ways - “whiskey” and “whisky.” Some people believe the extra “e” was added by Irish and American distilleries to differentiate their higher quality whiskeys during a period when Scottish whisky had a bad reputation.
Scotch was also introduced to denominate a Scottish whisky, and the word “whiskey” has been adopted in other countries for quite different reasons. In some South American countries, it’s used as an alternative to “cheese” to encourage people to smile when being photographed. How and why we chose “cheese,” and why the South Americans chose “whiskey” (and the Spanish patata, or “potato”) is a story for another time.