prayer flag noun1 •A colourful rectangular cloth hung from a thread and strung along mountain ridges and peaks high in the Himalayas by practitioners of Tibetan Buddhism to bless the surrounding countryside or for other purposes.On the final night of his journey, he strung up the inflated balloons at Duchala, a sacred mountain pass at 10,000 feet, bobbing amidst Buddhist prayer flags. — 2011 formsprayer flags