Definition of "pertinacious"
pertinacious
adjective
comparative more pertinacious, superlative most pertinacious
Holding tenaciously to an opinion or purpose.
Quotations
When that divine took his leave, not a little discomfited and amazed at the pertinacious obstinacy of the women, Laura repeated her embraces and arguments with tenfold fervour to Helen, who felt that there was a great deal of cogency in most of the latter.
1848 November – 1850 December, William Makepeace Thackeray, chapter 22, in The History of Pendennis. […], volumes (please specify |volume=I or II), London: Bradbury and Evans, […], published 1849–1850
He would really have to make up his mind to care for his wife or not to care for her. What would Lady Vandeleur say to one alternative, and what would little Joscelind say to the other? That is what it was to have a pertinacious father and to be an accommodating son.
1884, Henry James, “The Path of Duty”, in The English Illustrated Magazine, 2(15): 240-256
For, whether they were attracted by the lantern, or by the unaccustomed smell of a white man for which they had been waiting for the last thousand years or so, I know not; but certainly we were presently attacked by tens of thousands of the most blood-thirsty, pertinacious, and huge mosquitoes that I ever saw or read of.
1886 October – 1887 January, H[enry] Rider Haggard, She: A History of Adventure, London: Longmans, Green, and Co., published 1887
Stubbornly resolute or tenacious.
Quotations
[O]ne of the Dissenters, which I could, but forbear, to name appeared to Dr. Sanderson to be so bold, so troublesome, and so illogical in the dispute, as forced patient Dr. Sanderson, who was then Bishop of Lincoln, and a moderator with other Bishops, to say, with an unusual earnestness, "That he had never met with a man of more pertinacious confidence, and less abilities, in all his conversation."
1678, Izaak Walton, The life of Dr. Sanderson, late Bishop of Lincoln (London: Printed for Richard Marriot) [without pagination or secitons]