What Character Was Removed from the Alphabet? (dictionary.com)
"The word ampersand came many years later when & was actually part of the English alphabet. In the early 1800s, school children reciting their ABCs concluded the alphabet with the &.
It would have been confusing to say βX, Y, Z, and.β So, the students said, βand per se and.β Per se means βby itself,β so the students were essentially saying, βX, Y, Z, and by itself and.β The term per se was used to denote letters that also doubled as words, such as the letter I (for βmeβ) and A. By saying βper se,β you clarified that you meant the symbol and not the word.
Over time, βand per se andβ was slurred together into the word we use today: ampersand. When a word comes about from a mistaken pronunciation, itβs called a mondegreen. (If you sing the wrong lyrics to a song, thatβs also known as a mondegreen.)"