pertinacious
adjective
per·ti·na·cious ˌpər-tə-ˈnā-shəs 
1
a
: adhering resolutely to an opinion, purpose, or design
b
: perversely persistent
2
: stubbornly tenacious
pertinaciously adverb
pertinaciousness noun
pertinacity
ˌpər-tə-ˈna-sə-tē
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.
Synonyms
- dogged
- insistent
- patient
- persevering
- persistent
- tenacious
See all Synonyms & Antonyms 
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 Web 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, Philly.com, 25 June 2018
Chris Brennan, Philly.com, 25 June 2018 Word History
Etymology
Latin pertinac-, pertinax, from per- thoroughly + tenac-, tenax tenacious, from tenēre
First Known Use
1583, in the meaning defined at sense 1a
pertinaciousness
noun
as in obdurateness
a steadfast adherence to an opinion, purpose, or course of action in spite of reason, arguments, or persuasion thanks to his pertinaciousness, he eventually succeeded where all others had failed Synonyms & Similar Words
Relevance
- obdurateness
- mulishness
- persistence
- opinionatedness
- obstinateness
- resolve
- pertinacity
- persistency
- stubbornness
- self-opinionatedness
- bullheadedness
- intransigence
- pigheadedness
- obstinacy
- obduracy
- determination
- doggedness
- hardheadedness
- willfulness
- recalcitrancy
- steadfastness
- obstreperousness
- defiance
- wrongheadedness
- self-will
- balkiness
- perseverance
- perversity
- implacability
- waywardness
- perverseness
- tenacity
- inexorability
- inflexibility
- tenaciousness
- inveteracy
- hardness
- strictness
- rigidity
- sternness
- rebelliousness
- anal-retentiveness
- immovableness
- adamancy
- firmness
- adamance
- insubordination
- recalcitrance
- rigidness
- relentlessness
- single-mindedness
- refractoriness
- cussedness
- immovability
- disobedience
- rigorousness
- unruliness
- intractability
- cantankerousness
- contumacy
- stick-to-itiveness
- contrariness
- frowardness
- rigor
- bloody-mindedness
- narrow-mindedness
Antonyms & Near Antonyms
- reasonableness
- receptivity
- acceptance
- receptiveness
- acquiescence
- flexibility
- reasonability
- pliantness
- pliableness
- pliability
- compliance
- subordination
- pliancy
- subordinateness
- obedience
- surrender
- willingness
- broad-mindedness
- docility
- submission
- open-mindedness
- yielding
- subservience
- subserviency
- slavishness
- ultracentrifugally
- ultracentrifugation
- ultracentrifugations
- ultracentrifuge
- ultracentrifuged
- ultracentrifuges
- ultracentrifuging
- ultracheap
- ultrachic
- ultracivilized
- ultraclean
- ultracold
- ultracommercial
- ultracompact
- ultracompetent
- ultracompetitive
- ultracondenser
- ultraconservatism
- ultraconservatisms
- ultraconservative
- ultraconservatives
- ultracontemporaries
- ultracontemporary
- ultraconvenient
- ultracool