1
the rapidity of sth
后接名词，表示某事物迅速的程度。
The rapidity of the change surprised everyone.
变化的速度让所有人惊讶。
迅速；急速；快速
先理解核心含义，再看它在真实句子里的用法。
迅速；急速；快速
the quality or state of being rapid; speed or quickness
The rapidity of the change surprised everyone.
变化的速度让所有人惊讶。
速度；迅速；快速的状态
speed, swiftness; the condition of being rapid
相对于光速的速度度量；定义为 artanh(v),其中 artanh 为双曲反正切,v 为速度(取光速 c=1)
A measure of velocity relative to the speed of light; defined as artanh(v), where artanh is the hyperbolic arctangent, and v = speed (with c = speed of light = 1).
粒子束中粒子相对于束轴的速度度量
A measure of the velocity of a particle in a beam relative to the beam's axis
The rapidity of the company's growth surprised everyone.
公司增长的速度让所有人感到惊讶。
She was impressed by the rapidity with which he finished the report.
他完成报告的速度之快给她留下了深刻的印象。
The rapidity of technological change makes it hard to keep up.
技术变革的迅速使得跟上步伐变得困难。
后接名词，表示某事物迅速的程度。
The rapidity of the change surprised everyone.
变化的速度让所有人惊讶。
后接从句，说明某动作或过程发生得有多快。
She was impressed by the rapidity with which he learned.
她对他学得之快印象深刻。
用作方式状语，强调速度之快。
The rumors spread with astonishing rapidity.
谣言以惊人的速度传播。
Not this
The rapidity growth of the city is amazing.
Use this
The rapid growth of the city is amazing.
rapidity 是名词，不能放在名词 growth 前作定语；表示“快速的增长”应使用形容词 rapid 修饰 growth。
Not this
He ran rapidity to the station.
Use this
He ran with rapidity to the station.
rapidity 是名词，不能直接作状语修饰动词 ran；构成方式状语时需加介词 with，即 with rapidity（迅速地）。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
变化之迅速
The rapidity of change in technology can be overwhelming.
技术变化之迅速可能令人不知所措。
以极快的速度
The disease spread with great rapidity.
这种疾病以极快的速度传播。
……的速度之快
The rapidity with which she learned English surprised everyone.
她学英语速度之快让所有人惊讶。
越来越快的速度
The increasing rapidity of urban development raises environmental concerns.
城市发展速度越来越快，引发了环境方面的担忧。
Use rapidity naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
rapid 本就表示“快速的”，加上名词后缀 -ity 变成名词“迅速”。想象跑步冲刺时那种飞快的状态。
语域：formal 常见场景：学术写作、正式报告、文学描写 该词多用于较正式的书面语，如学术文章、正式报告或文学描写；日常口语中通常更常用 speed 或 quickness。
这些以 -idity 结尾的词（stupidity, humidity, timidity, validity, solidity）与 rapidity 同韵；拼写相近的 rapid 发音不同（/ˈræpɪd/），不押韵。
Dictionary facts from ECDICT, WIKTIONARY.