Definition of @ in English:

@

  • 1Used in internet addresses between the user's name and the domain name.

    • ‘jscott@oup.com’
    1. 1.1(in an online discussion, especially on the social media application Twitter) used preceding the name of a person in order to draw their attention to a comment or post, typically one that is directed to them.
      • ‘@Oliver: I'm aware of that fact’
  • 2‘at,’ used to indicate cost or rate per unit.

    • ‘30 dictionaries @$60.00 each’

transitive verb@s, @ing, @ed

[with object]informal
  • (in an online discussion, especially on Twitter) address (someone) in order to draw their attention to a comment or post, by using an @ symbol preceding their name.

    • ‘if you see anything else interesting, please @ me in the comments’