Dictionary
per•ti•na•cious
Pronunciation: (pûr"tn-ā'shus), [key]—
adj.
1. holding tenaciously to a purpose, course of action, or opinion; resolute.
2. stubborn or obstinate.
3. extremely or objectionably persistent:
a pertinacious salesman from whom I could not escape. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.