[ ˌdʌɪə'peɪs(ə)n , -z- ]
■ noun
1》 (also open ~ or stopped ~ ) an organ stop sounding a main register of flue pipes, typically of eight-foot pitch.
2》 a grand swelling burst of harmony.
Origin
ME (denoting the interval of an octave): via L. from Gk dia pasōn (khordōn) 'through all (notes)'.