Pronunciation: (pûr"tn-ā'shus), [key]
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.