What does rapidity mean?

Definitions for rapidity
rəˈpɪd ɪ ti; ˈræp ɪd nɪsra·pid·i·ty

This dictionary definitions page includes all the possible meanings, example usage and translations of the word rapidity.

Princeton's WordNet

  1. celerity, quickness, rapidity, rapidness, speedinessnoun

    a rate that is rapid


  1. rapiditynoun

    speed, swiftness; the condition of being rapid

  2. rapiditynoun

    A measure of velocity relative to the speed of light

  3. rapiditynoun

    A measure of the velocity of a particle in a beam relative to the beam#s axis

Samuel Johnson's Dictionary

  1. Rapiditynoun

    Celerity; velocity; swiftness.

    Etymology: rapidité, Fr. rapiditas, from rapidus, Lat.

    Where the words are not monosyllables, we make them so by our rapidity of pronunciation. Joseph Addison, Spectator.


  1. Rapidity

    In relativity, rapidity is commonly used as a measure for relativistic velocity. Mathematically, rapidity can be defined as the hyperbolic angle that differentiates two frames of reference in relative motion, each frame being associated with distance and time coordinates. For one-dimensional motion, rapidities are additive whereas velocities must be combined by Einstein's velocity-addition formula. For low speeds, rapidity and velocity are proportional but, for higher velocities, rapidity takes a larger value, with the rapidity of light being infinite. Using the inverse hyperbolic function artanh, the rapidity w corresponding to velocity v is w = artanh(v / c) where c is the velocity of light. For low speeds, w is approximately v / c. Since in relativity any velocity v is constrained to the interval −c < v < c the ratio v / c satisfies −1 < v / c < 1. The inverse hyperbolic tangent has the unit interval (−1, 1) for its domain and the whole real line for its image; that is, the interval −c < v < c maps onto −∞ < w < ∞.


  1. rapidity

    Rapidity refers to the speed or swiftness of an action or event. It also has specific meanings in different scientific contexts. In physics, for instance, "rapidity" is used to describe the velocity of a particle in relativistic motion.

Webster Dictionary

  1. Rapiditynoun

    the quality or state of being rapid; swiftness; celerity; velocity; as, the rapidity of a current; rapidity of speech; rapidity of growth or improvement


  1. Rapidity

    In relativity, rapidity is an alternative to speed as a measure of motion. On parallel velocities rapidities are simply additive, unlike speeds at relativistic velocities. For low speeds, rapidity and speed are proportional, but for high speeds, rapidity takes a larger value. The rapidity of light is infinite. The rapidity concept is not widely used; speed has the advantage of more direct measurability. Using the inverse hyperbolic function tanh−1, the rapidity φ corresponding to velocity v is φ = tanh−1. For low speeds, φ is approximately v/c. The speed of light c being finite, any velocity v is constrained to the interval -c

How to pronounce rapidity?

How to say rapidity in sign language?


  1. Chaldean Numerology

    The numerical value of rapidity in Chaldean Numerology is: 4

  2. Pythagorean Numerology

    The numerical value of rapidity in Pythagorean Numerology is: 3

Examples of rapidity in a Sentence

  1. Afia Salam:

    The rapidity of these events is increasing and our response is not keeping pace, we are being reactive to individual events. Strategies need to be put in place.

  2. William Richardson Davie:

    So low and hopeless are the finances of the United States, that, the year before last Congress was obliged to borrow money even, to pay the interest of the principal which we had borrowed before. This wretched resource of turning interest into principal, is the most humiliating and disgraceful measure that a nation could take, and approximates with rapidity to absolute ruin: Yet it is the inevitable and certain consequence of such a system as the existing Confederation.

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Translations for rapidity

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"rapidity." Definitions.net. STANDS4 LLC, 2024. Web. 18 Jun 2024. <https://www.definitions.net/definition/rapidity>.

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    a wild and exciting undertaking (not necessarily lawful)
    A carry
    B conceal
    C acclaim
    D adventure

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