the fact that there is no single word in English for the symbol has prompted some writers to use the French arobase or Spanish and Portuguese arroba, or to coin new words such as the “highly logical” ampersat,asperand, and the strudel, but none of these has achieved wide use. https://en.wikipedia.org/wiki/At_sign
The ampersand is the sign &, used to mean ‘and’. The shape of the symbol originated as a ligature for the Latin et(‘and’) – that is, it represents the merged ‘e’ and ‘t’. The name ampersand also represents a merge, although one that is perhaps more accidental.
When reciting the alphabet, letters that were also entire words in and of themselves (such as a and I) could once be read as ‘a per se a’, ‘i per se I’, to make it clear that a word was intended, rather than a single letter. Per se is the Latin for ‘by itself’, so the & symbol, which was traditionally included at the end of the alphabet, was originally chanted as ‘and per se and’ (that is, ‘& by itself is and’). Over time, this was altered into the single word ampersand, and the original phrase was largely forgotten. The same could possibly be said about ampersat and the sign @. https://blog.oxforddictionaries.com/2015/03/25/signs-and-symbols-the-names-of-punctuation-marks/
Whatever the origin of the @ symbol, the history of its usage is more well-known: it has long been used in Spanish and Portuguese as an abbreviation of arroba, a unit of weight equivalent to 25 pounds, and derived from the Arabic expression of “the quarter” (الربع pronounced ar-rubʿ). An Italian academic, Giorgio Stabile, claims to have traced the @ symbol to the 16th century, in a mercantile document sent by Florentine Francesco Lapi from Seville to Rome on May 4, 1536. The document is about commerce with Pizarro, in particular the price of an @ of wine in Peru. In Italian, the symbol was interpreted to mean amphora (anfora). Currently, the word arroba means both the at-symbol and a unit of weight. In Italian, the symbol represents one amphora, a unit of weight and volume based upon the capacity of the standard amphora jar.
Until now the first historical document containing a symbol resembling a @ as a commercial one is the Spanish “Taula de Ariza”, a registry to denote a wheat shipment from Castile to Aragon in 1448; even though the oldest fully developed modern @ sign is the one found on the above-mentioned Florentine letter.https://en.wikipedia.org/wiki/At_sign