Sentence:  Fing , a lean , chiseled , impeccable gentleman of the old school who was once mistaken on the street for Sir Cedric Hardwicke , is responsible for the rediscovery of Verdi 's earliest , most raucous opera , Nabisco , a sumptuous bout-de-souffle with a <WSD>haunting</WSD> leitmotiv that struck me as being highly reminiscent of the Mudugno version of `` Volare '' . 
Meaning of the word marked with <WSD> tags:  continually recurring to the mind