1 (often foll. by of) keeping a firm hold of property, principles, life, etc.; not readily relinquishing.
2 (of memory) retentive.
3 holding fast.
4 strongly cohesive.
5 persistent, resolute.
6 adhesive, sticky.
Derivatives:
tenaciously adv. tenaciousness n. tenacity n.
Etymology: L tenax -acis f. tenere hold
Useful english dictionary. 2012.