Remove the first syllable of pertinacious and say what remains out loud: you'll hear something that sounds a lot like the word tenacious, meaning "tending to adhere or cling." The similarity between pertinacious and tenacious isn't mere coincidence; both words derive from tenax, the Latin word for "tenacious," and ultimately from the verb tenēre, meaning "to hold." Another descendant of tenēre is tenure, a word that is typically used of the right to hold a job (especially a teaching position) for as long as desired.
obstinate implies usually an unreasonable persistence.
an obstinate proponent of conspiracy theories
dogged suggests an admirable often tenacious and unwavering persistence.
pursued the story with dogged perseverance
stubborn implies sturdiness in resisting change which may or may not be admirable.
a person too stubborn to admit error
pertinacious suggests an annoying or irksome persistence.
a pertinacious salesclerk refusing to take no for an answer
mulish implies a thoroughly unreasonable obstinacy.
a mulish determination to have his own way
Example Sentences
a pertinacious little boy who was determined to catch and collect reptiles a pertinacious salesman who would simply not take “No!” for an answer
Recent Examples on the WebBarletta’s pertinacious reputation on immigration, from his time as mayor of Hazleton to his four terms in the U.S. House, is at center stage this year in his campaign to defeat Sen. Bob Casey’s bid for a third term. Chris Brennan, Philly.com, 25 June 2018
Word History
Etymology
Latin pertinac-, pertinax, from per- thoroughly + tenac-, tenax tenacious, from tenēre