Definition of pertinacity in US English:

pertinacity

noun

formal
  • See pertinacious

    • ‘I want no greater proof of the corruption of human nature than the pertinacity with which we seek happiness where happiness cannot be found.’
    • ‘This was returned to Buckingham Palace in 1947, largely through the pertinacity of Queen Mary.’
    • ‘In both instances, it's a good advertisement for pertinacity.’
    • ‘The gravity which Albert applied to court life in the south was applied with equal pertinacity to the serious business of recreation in the north.’
    • ‘If, in the face of these facts, somebody still insists that the boundaries of the Sikh religion are blurred, it is sheer pertinacity.’

Pronunciation

pertinacity

/ˌpərtnˈæsədi//ˌpərtnˈasədē/