remarkable rapidness 惊人的速度
the rapidness of change 变化的迅速
with great rapidness 极快地
A: How did you react to the rapidness of the decision?
A：你对那个决定的迅速做出什么反应？
B: I was caught off guard by its rapidness.
B：它的迅速程度让我措手不及。
1) 快速，迅速
2) 敏捷，快捷
1. 快速，迅速
noun
1. The quality or state of being rapid; speed or swiftness.
Synonym: speed, swiftness, velocity