The name of this Eastern European spirit probably comes from "voda," or water, in Russian. Similarly, the same word in Polish is "woda." This is a common pattern in completely unrelated languages; Whiskey/Whisky in English is derived from Gaelic uisge beatha, which quite literally means "water of life," from Old Irish uisce "water" + bethu "life." The Gaelic is itself probably a literal translation of the Medieval Latin aqua vita, which also gives us Akevitt, or Aquavit or Akvavit, in various Scandinavian languages.

There's a good bit of dispute as to whether the Russians or the Poles developed vodka first. But by the late middle ages, vodka was the strong spirit of choice for Russians and much of Eastern Europe. Vodka was considered to have both medicinal and religious properties. And certainly by 1533, vodka was in widespread medicinal use in Russia, according to the Novgorod Chronicles, administered both internally and externally.

The original vodka would have been distilled from grains, primarily rye, however. Oddly enough, making vodka from potatoes was a relatively late development in the history of the spirit. During the Napoleanic Wars, vodka's popularity swiftly spread across Europe. The increasing demand meant that less expensive, readily available ingredients were needed to distill the stuff. Vodka makers started using potato mash, since potatoes were plentiful and cheap.