Earstone, ecotone, elute, embrue and elaphine are just a few of the hundreds of unique English words that begin and end with the letter "E." The letter is the most commonly used letter in the English language. As of November 2015, WordsThatStart.com lists 485 words that begin and end with the letter "E."
Many uncommon words of this type begin with the prefix "en-." These include ensphere, engramme, enisle, ensilage and ennuyee, which means a woman affected with ennui. The same is true of the prefix "ex-." Examples include excide, exergue, exertive, exigence and exigible.
Short uncommon words that meet this criteria include eyne, eyre and erne. Longer words include eupatridae, euxenite, extirpate, extravasate and endamebae, which are parasites that live in the digestive tracts of cockroaches. An extraordinarily long word that begins and ends with "E" is ethylenediaminetetraacetate at 27 letters long. It is the name of an acid commonly used to dissolve limescale.
Several uncommon words like this contain the word eye, which is one of the shortest words that begin and end with the letter "E." These unusual "eye" words include eyeable, eyehole, eyelike and eyestone.
According to the WordsThatStart.com list, there are no words that start with "Ez-" and end with an "E." Every other letter, however, following the initial "E," can be used to create a word that meets this criteria.