The ampersand symbol (&) is now primarily used in business names, but it was once the 27th letter of the alphabet. Its name actually came from a bizarre origin story from the early 1800s when school children reciting their ABCs concluded the alphabet with the symbol. The students would confuse the phrase “X, Y, Z, and,” so they would say “and per se and.” As a result of slurring the phrase together, the word ampersand was born. The character’s shape predates the word itself by more than 1,500 years, having originated from linking the letters E and T in cursive Latin script to indicate the word ‘and.’
https://www.dictionary.com/e/ampersand/