Definition of srsly in English:

srsly

adverb

informal
  • Seriously:

    ‘do you srsly think you will gain anything?’
    [as sentence adverb] ‘srsly though, I see where you're coming from’
    [as submodifier] ‘it is a srsly cool bike’
    • ‘Srsly, this is a cool vid even if you aren't in fandom, though it's really a love letter to all the fans out there.’
    • ‘I think I went slightly bug-eyed at this point and went "SRSLY?"’
    • ‘Srsly, if you're already going to concede wiredness (and I do), then it stands to reason that you want a full-function keyboard.’
    • ‘Srsly, cover up the shoes with your thumb and imagine flats.’
    • ‘If you're srsly about being polite, read this again.’
    • ‘Srsly thank god for my awesome classmates.’
    • ‘Srsly, they say it's gonna get bad.’
    • ‘Srsly though, I think their defense and lack thereof is going to have a cascading effect on the team this year.’
    • ‘And for the love of all that is holy, NO ATTACHMENTS (like srsly, we'll toss your application).’

Origin

Late 18th century: abbreviation (first recorded in a manual on shorthand).