A plainsong melody serving as the basis of a polyphonic composition by the addition of contrapuntal voices, as in 5th-century polyphony.

固定旋律，固定曲调：与对位声部一起作为一首复调音乐基础的一段素歌旋律，如在5世纪复调音乐中。

youdao

If you put in other little strands of melody, it changes it more toward polyphonic texture.

如果将之放到其他的小旋律中，将会改变对位材质。

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