"the relentless beat of the drums"

"haunting memories"
"the cathedral organ and the distant voices have a haunting beauty"

"persistent leaves remain attached past maturity"
"the persistent gills of fishes"

"dogged persistence"
"dour determination"
"the most vocal and pertinacious of all the critics"
"a mind not gifted to discover truth but tenacious to hold it"
"men tenacious of opinion"