Definition of whereof in English:

whereof

relative adverb

formal
  • Of what or which.

    ‘I know whereof I speak’
    • ‘Any woman who has just delivered a baby knows whereof I speak.’
    • ‘I worked for years for some of them, so I know whereof I speak.’
    • ‘When it comes to Germans and their relationship with dictators, Enzensberger knows whereof he speaks.’
    • ‘I've met a few in my day, so I know whereof I speak.’
    • ‘Sharon Leach wrote in the Sunday Observer of the agonies of having to do without water, and she knows whereof she speaks.’
    • ‘Good taste dictates that more than two times out of the gate calls for the simplest of celebrations - and Prudie knows whereof she speaks.’
    • ‘Bell is a pharmacist and knows whereof she speaks.’
    • ‘As someone who used to write for them, I know whereof I speak when I say that the New York Press is irrelevant.’
    • ‘Talab al-Sana'i, an Arab member of the Israeli Knesset, is one of Amayrah's key sources, and it seems likely to me that he knows whereof he speaks.’
    • ‘UN envoy to Iraq Lakhdar Brahimi knows whereof he speaks when it comes to civil war.’
    • ‘The back-cover biography assures you in rampant detail that he knows whereof he speaks.’
    • ‘‘Cookie companies have been making your lifestyle choices for you,’ says the outspoken Powter, who once weighed 260 pounds and knows whereof she speaks.’
    • ‘Never before have I seen people fight with such viciousness and hatred - and I speak whereof I know as I was at the First Day Sales at McGringles this year.’
    • ‘I think there are far more issues here than can be resolved by a simple ‘I have been there, and know whereof I speak’.’
    • ‘When Chinese dissenters claim that Chinese socialism is a form of feudalism they know whereof they speak.’
    • ‘Michnik knows whereof he speaks and writes, unlike so many of those in the European media who are busy gnawing at the supports of the trans-Atlantic alliance.’
    • ‘Consider the risk of not acting: the creeping falseness and constraint that comes of an important unacknowledged truth between you (I know whereof I speak).’
    • ‘It's full of the stuff that packs the dance floor: a defiant but dignified message of survival sung by a woman who knows whereof she speaks.’
    • ‘Spencer is a historian who knows whereof he speaks.’
    • ‘Because, and believe me I know whereof I speak, the world is "full" of people who think they have the right to be obnoxious about your parenting choices.’

Pronunciation

whereof

/wɛːrˈɒv/