From dictionary.com:



  1. holding tenaciously to a purpose, course of action, or opinion; resolute.
  2. stubborn or obstinate.
  3. extremely or objectionably persistent.



  1. pertaining or relating directly and significantly to the matter at hand; relevant.

I can't find anything in common in terms of their meaning. Although,

Pertinent:from Latin pertinēns, from pertinēre to pertain

Pertinacious:1620-30; pertinaci(ty) + -ous

And pertinent is related to pertinence, which looks similar to pertinacious. Is it a coincidence?

Let me know if these questions are not constructive, I'll stop posting. By the way, I'm studying vocabulary for English test so I'm trying to find a way to memorize words that look similar otherwise I'll have to do it all by rote.

  • Here's a text from 1816 setting out usage differences. But personally, I wouldn't bother wasting brain cells remembering pertinacious at all. It's very rarely used today, and usually when it is used it's just a pretentious alternative to tenacious anyway. Besides, I doubt it would be likely to turn up in a vocabulary test. – FumbleFingers May 19 '15 at 12:56

They actually both derive from PER and TENET

Pertinacious:( 1620s, from pertinacy (late 14c.; see pertinacity):

  • pertinacity
  • c. 1500, from Middle French pertinacité (early 15c.), from Old French pertinace "obstinate, stubborn," from Latin pertinacem (nominative pertinax) "very firm, tenacious, steadfast, persevering," from per- "very" (see per) + tenax (see tenacious). It drove out earlier pertinacy (late 14c.).

  • tenacious (adj.) c. 1600, from Latin stem of tenacity + -ous.

  • tenacity (n.) early 15c., from Middle French ténacité (14c.) and directly from Latin tenacitas "an act of holding fast," from tenax (genitive tenacis) "holding fast, gripping, clingy; firm, steadfast," from tenere "to hold" (see tenet).


  • late 14c., from Anglo-French purtinaunt (late 13c.), Old French partenant (mid-13c.) and directly from Latin pertinentem (nominative pertinens) "pertaining," present participle of pertinere "to relate, concern" (see pertain).

  • pertain (v.):early 14c., from Old French partenir "to belong to" and directly from Latin pertinere "to reach, stretch; relate, have reference to; belong, be the right of; be applicable," from per- "through" (see per) + tenere "to hold" (see tenet).

form Etymonline


The answer is actually yes.

Latin (per)tinax and (per)tinens are both related to the verb tenere "to hold". pertinax is literally "holding fast to something".

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