The Collaborative International Dictionary
Pertinaciousness
Pertinacious \Per`ti*na"cious\, a. [L. pertinax, -acis; per + tenax tenacious. See Per-, and Tenacious.]
Holding or adhering to any opinion, purpose, or design, with obstinacy; perversely persistent; obstinate; as, pertinacious plotters; a pertinacious beggar.
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Resolute; persevering; constant; steady.
Diligence is a steady, constant, and pertinacious study.
--South.Syn: Obstinate; stubborn; inflexible; unyielding; resolute; determined; firm; constant; steady. [1913 Webster] -- Per`ti*na"cious*ly, adv. -- Per`ti*na"cious*ness, n.
Wiktionary
pertinaciousness
n. The state or characteristic of being pertinacious.