Definition of @ in US English:

@

  • 1‘at,’ used to indicate cost or rate per unit.

    ‘30 dictionaries @$60.00 each’
  • 2Used in Internet addresses between the user's name and the domain name.

    ‘jscott@oup.com’
    1. 2.1 (in an online discussion, especially on the social media application Twitter) preceding the name of a person to whom a comment is directed.
      ‘@Oliver: I'm aware of that fact’