GRE Vocab

I have two questions.

  1. When we learn synonyms, let’s say pertinacious’s synonyms are persistent, refractory, obdurate, tenacious. But tenacious’s synonyms are diligent, staunch, steadfast. So, should I learn the last three as the synonyms of pertinacious??

  2. In SE questions, do ETS set a trap by keeping nuance synonyms such as stingy and miser?

Hey,
Pertinacious aligns with ‘stubbornness’ and all the words related with it are it’s synonyms. Tenacious have multiple meanings. One meaning is ‘firm’ which is inclined to pertinacious.
The other meaning for tenacious is ‘never give up’. So, this has different synonyms.
Stingy and miserly are clearly synonyms.