Phu (ภู) comes from the Thai word Phukao (ภูเขา), meaning mountain. The name Kradueng (กระดึง), or Krading (กระดิ่ง) in the local dialect of Loei Province, can be translated as Rakhang Yai (ระฆังใหญ่), meaning a large bell. This name comes from a legend relating to a Buddhist holiday. During the holiday many of the towns people heard the sound of a large bell. They believed it to be the bell of Indra.