Definition of perniciousness in US English:

perniciousness

noun

  • See pernicious

    • ‘Let us take the lead in recognising the perniciousness of an ethos that thinks it is destined to rule the world.’
    • ‘That kind of double talk, that perniciousness should be stopped immediately.’
    • ‘In fact, its perniciousness has spread well beyond startups.’
    • ‘The true perniciousness of uncertainty is economic in origin and effect.’
    • ‘However, geneticists began criticizing him for his antiscientific declarations regarding the perniciousness of genetics.’

Pronunciation

perniciousness

/pərˈnɪʃəsnəs//pərˈniSHəsnəs/