A rash is something that spreads like wild fire — red itchy skin or a series of unfortunate events. It can also describe an impulsive, wild decision.

As an adjective, rash has meant "quick, vigorous" since the 1300s by way of Scotland. The meaning shifted to "reckless" a few hundred years later, and can still be used that way — a "rash decision" is a sudden, not well thought out one. Rash, the noun that no one wants on their skin, came a few hundred years after that, but from the French word rache which at some point meant "ringworm." Ringworm still gives us a red, itchy rash. Fun! Rash can also mean a lot of unpleasant things happening in a short amount of time, like robberies or earthquakes.

Definitions of rash
  1. adjective
    imprudently incurring risk
    “"do something rash that he will forever repent"- George Meredith”
    not prudent or wise
  2. adjective
    marked by defiant disregard for danger or consequences
    “a rash attempt to climb Mount Everest”
    synonyms: foolhardy, heady, reckless
    fearless and daring
  3. noun
    any red eruption of the skin
    synonyms: efflorescence, roseola, skin rash
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    heat rash, miliaria, prickly heat
    obstruction of the sweat ducts during high heat and humidity
    hives, nettle rash, urticaria, urtication
    an itchy skin eruption characterized by weals with pale interiors and well-defined red margins; usually the result of an allergic response to insect bites or food or drugs
    type of:
    symptom consisting of a breaking out and becoming visible
  4. noun
    a series of unexpected and unpleasant occurrences
    “a rash of bank robberies”
    synonyms: blizzard
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    type of:
    similar things placed in order or happening one after another
Word Family

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