persistent
per.sis.tent \-t*nt\ aj [L persistent-, persistens, prp. of persistere] 1a:
continuing or inclined to persist in a course 1b: continuing to exist in
spite of interference or treatment {a ~ cough} 2: existing for a long or
longer that usual time or continuously : as 2a: retained beyond the usual
period {a ~ leaf} 2b: continuing without change in function or structure
{~ gills} 2c: effective in the open for an appreciable time usu. through
slow volati lizing {mustard gas is ~} - per.sis.tent.ly av