We were taught at school to call it the “at sign,” as in:
three apples @ 20p = 60p (three apples AT 20p [each] equals 60p)
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In English, its hijacking for use in email addresses makes sense: j.smith AT domain.com etc.
However, some other languages that didn’t use it much prior to the advent of email have (perfectly understandably) missed the point, as it were. In Hungarian it’s called ‘kukac,’ which means ‘maggot’ or ‘worm’ (or even, in the right context, a certain male appendage). IIRC in another Euroean language (I can’t remember which, but possibly even more than one) it’s called a snail.
A Hungarian dictating an email address - even in a formal or business context - literally says: “j.smith, WORM, domain.com.”
[/slight hijack]