Source : Webster's Revised Unabridged Dictionary (1913)

Rash \Rash\, a. [Compar. {Rasher}; superl. {Rashest}.] [Probably
   of Scand. origin; cf. Dan. & Sw. rask quick, brisk, rash,
   Icel. r["o]skr vigorous, brave, akin to D. & G. rasch quick,
   of uncertain origin.]
   1. Sudden in action; quick; hasty. [Obs.] ``Strong as
      aconitum or rash gunpowder.'' --Shak.

   2. Requiring sudden action; pressing; urgent. [Obs.]

            I scarce have leisure to salute you, My matter is so
            rash.                                 --Shak.

   3. Esp., overhasty in counsel or action; precipitate;
      resolving or entering on a project or measure without due
      deliberation and caution; opposed to prudent; said of
      persons; as, a rash statesman or commander.

   4. Uttered or undertaken with too much haste or too little
      reflection; as, rash words; rash measures.

   5. So dry as to fall out of the ear with handling, as corn.
      [Prov. Eng.]

   Syn: Precipitate; headlong; headstrong; foolhardy; hasty;
        indiscreet; heedless; thoughtless; incautious; careless;
        inconsiderate; unwary.

   Usage: {Rash}, {Adventurous}, {Foolhardy}. A man is
          adventurous who incurs risk or hazard from a love of
          the arduous and the bold. A man is rash who does it
          from the mere impulse of his feelings, without
          counting the cost. A man is foolhardy who throws
          himself into danger in disregard or defiance of the
          consequences.

                Was never known a more adventurous knight.
                                                  --Dryden.

                Her rush hand in evil hour Forth reaching to the
                fruit, she plucked, she eat.      --Milton.

                If any yet to be foolhardy To expose themselves
                to vain jeopardy; If they come wounded off, and
                lame, No honors got by such a maim. --Hudibras.