PERSISTENT

adjective Etymology: Latin ~-, persistens, present participle of persistere Date: 1826 existing for a long or longer than usual time or continuously: as, retained beyond the usual period , continuing without change in function or structure , effective in the open for an appreciable time usually through slow volatilizing , degraded only slowly by the environment , remaining infective for a relatively long time in a vector after an initial period of incubation , 2. continuing or inclined to persist in a course, continuing to exist in spite of interference or treatment , ~ly adverb