Wiktionary
commercial at
n. 1 The symbol @, read "at", used to denote per unit price: 2 This symbol used in e-mail addresses to separate the domain name from the rest of the address.
Usage examples of "commercial at".
But I did my first television commercial at fourteen and I was hooked.
Now, you know, sir, as a rule, a busy gentleman won't see a commercial at all if he's not interested in the goods.