per·​ti·​na·​cious ˌpər-tə-ˈnā-shəs How to pronounce pertinacious (audio)
: adhering resolutely to an opinion, purpose, or design
: perversely persistent
: stubbornly tenacious
pertinaciously adverb
pertinaciousness noun
pertinacity noun

Did you know?

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.

Choose the Right Synonym for pertinacious

obstinate, dogged, stubborn, pertinacious, mulish mean fixed and unyielding in course or purpose.

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

Examples of pertinacious in a Sentence

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 Web But Kerry, the pertinacious diplomat and former Massachusetts senator, sees too much to do — and insisted in an interview with The Boston Globe there is too much to possibly achieve — to quit just yet. Jess Bidgood,, 26 Feb. 2023 Barletta’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,, 25 June 2018

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'pertinacious.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Latin pertinac-, pertinax, from per- thoroughly + tenac-, tenax tenacious, from tenēre

First Known Use

1583, in the meaning defined at sense 1a

Time Traveler
The first known use of pertinacious was in 1583


Dictionary Entries Near pertinacious

Cite this Entry

“Pertinacious.” Dictionary, Merriam-Webster, Accessed 12 Jul. 2024.

Kids Definition


per·​ti·​na·​cious ˌpərt-ᵊn-ˈā-shəs How to pronounce pertinacious (audio)
: holding strongly to an opinion, purpose, or course of action
: stubbornly or annoyingly persistent
pertinaciously adverb
pertinaciousness noun
pertinacity noun
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