Estonian word meaning "edge of the ice". Not very many words have four consecutive vowels.

Jäääärne is actually an adjective characterizing an item as being on the edge of the ice. "Jäääär" is the noun, "edge of the ice"; it is also the name of a very popular Estonian band. A semiartificial word in Estonian that has even more vowels is "töööööök" (retch of the working night).