Deffo

//ˈdɛfəʊ// adj, adv, slang

adj, adv, slang ·Moderate ·College level

Definitions

Adjective
  1. 1
    Definite. Australia, Canada, Ireland, UK, colloquial, usually

    "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."

Adverb
  1. 1
    Definitely. Australia, Canada, Ireland, UK, colloquial

    "He told me that he's deffo going to be there tonight."

Synonyms

All synonyms
defdeffosdefs

Example

More examples

"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."

Etymology

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

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.