[per.sis.tent] adj [L persistent-, persistens, prp. of persistere] (1826) 1: existing for a long or longer than usual time or continuously: as a: retained beyond the usual period "a ~ leaf" b: continuing without change in function or structure "~ gills" c: effective in the open for an appreciable time usu. through slow volatilizing "mustard gas is ~" d: degraded only slowly by the environment "~ pesticides" e: remaining infective for a relatively long time in a vector after an initial period of incubation "~ viruses"
2. a: continuing or inclined to persist in a course b: continuing to exist in spite of interference or treatment "a ~ cough" -- per.sis.tent.ly adv