“At this last question, following so many pertinacious ones, for he soul of him Captain Delano could not but look very earnestly at the questioner.” — Benito Cereno
“since then, the bees kept coming thither, Heaven knows why, or by what pertinacious desire, for far-fetched sweets” — House of the Seven Gables
“There was something in the moody and dogged silence of this pertinacious companion” — Sketchbook of Geoffrey Crayon
Found in three of my favorite authors is a lovely word that is rarely used anymore, mostly because it has been absorbed by its less extreme cousin. Tenacious comes from the Latin verb “to hold.” Pertinacious would mean “to hold through.” It seems to imply being tenacious through difficulty. It carries a more negative connotation in its use as well, a stubbornness.