When creating a new typeface, a designer can inject the most artistic flair into the ampersand character. The term ampersand, as Geoffrey Glaister writes in his "Glossary of the Book," is a corruption of and (&) per se and, which literally means "(the character) & by itself (is the word) and." The symbol & is derived from the ligature of ET or et, which is the Latin word for "and."

http://www.adobe.com/type/topics/theampersand.html

As seen on the Ressabiator Blog