Ampersand

An ampersand (&), also commonly called an " 'and' sign," is a logogram representing the conjunction "and". The symbol is a ligature of the letters in et, Latin for "and". Its origin is apparent in the images shown below.

The word ampersand is a corruption of the phrase "and per se and", meaning "and [the symbol which] by itself [is] and". The Scots and Scottish English name for & is epershand, derived from "et per se and", with the same meaning.

Traditionally, in English-speaking schools when reciting the Alphabet, any letter that could also be used as a word in itself ("A," "I," "&" and, at one point, "O") was preceded by the Latin expression "per se" (Latin for "by itself"). Also, it was common practice to add at the end of the alphabet the "&" sign, pronounced "and". Thus, the recitation of the alphabet would end in: "X, Y, Z and per se and." This last phrase was routinely slurred to "ampersand" and the term crept into common English usage by around 1837.

Through folk etymology, it has been claimed that André-Marie Ampère used the symbol in his widely read publications, and that people began calling the new shape "Ampere's and."

Source: http://en.wikipedia.org/wiki/Ampersand