From set +‎ -ness.

setness (countable and uncountable, plural setnesses)

1. The quality or state of being set; formality; obstinacy.
   • 1884, Robert Masters, Memoirs […] of Thomas Baker:

     the starched setness of a sententious writer

   • 1851 June – 1852 April, Harriet Beecher Stowe, Uncle Tom’s Cabin; or, Life among the Lowly, volume (please specify |volume=I or II), Boston, Mass.: John P[unchard] Jewett & Company; Cleveland, Oh.: Jewett, Proctor & Worthington, published 20 March 1852, →OCLC:

     They who had shrugged their shoulders at her little peculiarities and setnesses […] acknowledged that now she was the exact person that was wanted.

• essents, sensest