From definitely or definite +‎ -o (diminutive suffix).



deffo (comparative more deffo, superlative most deffo)

  1. (slang, Australia, Britain, Ireland, usually with "for") Definite.
    • 2003, Grace Dent, LBD: it′s a girl thing, page 45,
      I know for certain they′re not speaking to each other, that′s for deffo, not that I′ve even seen them in the same room over the last week to confirm their silence.
    • 2009, Joe Stretch, Wildlife, unnumbered page,
      ‘An infection. Nothing serious. They′ll have some colour in them soon, for deffo.’
    • 2009, Stephen Leonard Lancashire, Immaculate Deception, page 271,
      “Couldn′t say for deffo, probably at least fifteen years old, but I know they don′t make them like these any more for exactly the reason you′ve just seen. The security systems shite.”
    • 2010, Simon Pegg, Nerd Do Well, page 25,
      Needles wilted under the force of Pegg′s demand, his eyes widened and he seemed to shrink in size, and I can′t say for deffo but I think he probably wet himself.


deffo (comparative more deffo, superlative most deffo)

  1. (slang, Australia, Britain, Ireland) Definitely.
    He told me that he's deffo going to be there tonight.
    • 2009, Nick Leather, Billy Wonderful, page 12,
      And I deffo don′t believe in me, cos I′m a proper knobhead, aren′t I, and always have been.
    • 2011, Andrew Fitzpatrick, Strictly Legal, page 128,
      It′s weird, but even though Dosser was only grounded for like two weeks, I was actually starting to kind of miss him, and I deffo would′ve loved to have gone for a good old-fashioned crow-hunt that Saturday afternoon, [] .
    • 2011, Maggie Graham, Me and My Animals, page 142,
      [] And no giving in at the slightest whimper. Agreed?’
      Deffo!’ He couldn′t see my fingers crossed behind my back.