pertinaciousness

From pertinacious + -ness.

pertinaciousness (uncountable)

1. The state or characteristic of being pertinacious.
   • 1805, Charles Brockden Brown, Wieland; and Memoirs of Carwin the Biloquist, Penguin Classics, published 1991, →ISBN, page 289:

     I had too much experience of my father's pertinaciousness ever to hope for a change in his views.

• pertinacity

• “pertinaciousness”, in OneLook Dictionary Search.