persistent

(pər-sĭsˈtənt, -zĭsˈ-)

1. Refusing to give up or let go; persevering obstinately.
2. Insistently repetitive or continuous: a persistent ringing of the telephone.
3. Existing or remaining in the same state for an indefinitely long time; enduring: persistent rumors; a persistent infection.
4. Botany Lasting past maturity without falling off, as the calyx on an eggplant or the scales of a pine cone.
5. Zoology Retained permanently, rather than disappearing in an early stage of development: the persistent gills of fishes.

Related Forms:

• per·sisˈtent·ly adverb