persistent

per·sis·tent

adj \-tənt\

Definition of PERSISTENT

1

: existing or continuing for a long time: as a : effective in the open for an appreciable time usually through slow volatilizing <mustard gas is persistent> b : degraded only slowly by the environment <persistent pesticides> c : remaining infective for a relatively long time in a vector after an initial period of incubation <persistent viruses>

2

: continuing to exist despite interference or treatment <a persistent cough> <has been in a persistent vegetative state for two years>