Pronunciation: (tu-nā'shus),[key] —adj. 1. holding fast; characterized by keeping a firm hold (often fol. by of): a tenacious grip on my arm; tenacious of old habits. 2. highly retentive: a tenacious memory. 3. pertinacious, persistent, stubborn, or obstinate.
4. adhesive or sticky; viscous or glutinous.
5. holding together; cohesive; not easily pulled asunder; tough.