Definition of so long! in US English:

so long!

phrase

informal
  • Goodbye until we meet again.

    • ‘I just want it to be done with, but I don't want to deal with any of the moving or saying so long stuff.’
    • ‘So long, Mother. Be expecting a postcard or two in the mail, if you're lucky.’
    • ‘When she walked out on the Sugababes as they hit the big time, it looked like so long, Siobhan.’
    • ‘‘So long!’, Catharine waved goodbye to Audrey as the door closed.’
    farewell, adieu
    View synonyms