D defs.my
Entry 1 sense Webster, 1913

Disdiapason

· Dis·di·a·pa·son · IPA
01 n. An interval of two octaves, or a fifteenth; -- called also bisdiapason. Compare diapason{1}.
  1. 1.
    An interval of two octaves, or a fifteenth; -- called also bisdiapason. Compare diapason{1}.(Anc. Mus.) Also: bisdiapason See: diapason{1}