Definition of instant message in English:

instant message

(also IM)

noun

  • A message sent via the Internet that appears on the recipient's screen as soon as it is transmitted.

    • ‘What other MSN or any instant messaging pet peeves do you have?’
    • ‘Blame it on its ability to let you do instant messaging, or real time messaging with your buddies all around the world.’
    • ‘For a long time instant messaging has allowed computer users to communicate over the internet using a text-based chat service.’
    • ‘Apparently movies flop because of texting, instant messaging and email.’
    • ‘With respect to an online dating service you could use Skype to allow someone to actually talk to the other person, rather than use instant messaging.’
    • ‘For the vast majority of its users, the Internet represents e-mail and instant messaging.’

verb

[WITH OBJECT]
  • Send (someone) an instant message.