The Collaborative International Dictionary of English v.0.48:

Rash \Rash\, a. [Compar. Rasher (-[~e]r); 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.
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   2. Requiring sudden action; pressing; urgent. [Obs.]
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            I scarce have leisure to salute you,
            My matter is so rash.                 --Shak.
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   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.
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   4. Uttered or undertaken with too much haste or too little
      reflection; as, rash words; rash measures.
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   5. So dry as to fall out of the ear with handling, as corn.
      [Prov. Eng.] --Grose.
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   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.
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                Was never known a more adventurous knight.
                                                  --Dryden.
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                Her rash hand in evil hour
                Forth reaching to the fruit, she plucked, she
                eat.                              --Milton.
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                If any yet be so foolhardy
                To expose themselves to vain jeopardy;
                If they come wounded off, and lame,
                No honor's got by such a maim.    --Hudibras.
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The Collaborative International Dictionary of English v.0.48:

Rasher \Rash"er\ (r[a^]sh"[~e]r), n. [In sense 1, probably fr.
   rash, a., as being hastily cooked.]
   1. A thin slice of bacon.
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   2. (Zool.) A California rockfish (Sebastichthys miniatus).
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WordNet (r) 3.0 (2006):

rasher
    n 1: a commercially important fish of the Pacific coast of North
         America [syn: vermillion rockfish, rasher, Sebastodes
         miniatus]

Moby Thesaurus II by Grady Ward, 1.0:

78 Moby Thesaurus words for "rasher":
   bit, butt, chip, chunk, clip, clipping, coat, coating, collop,
   covering, crumb, cut, cutting, deal, disk, dollop, end, feuille,
   film, flap, foil, fold, fragment, gob, gobbet, hunk, lamella,
   lamina, laminated glass, laminated wood, lap, leaf, lump, membrane,
   modicum, moiety, morsel, pane, panel, paring, particle, patina,
   peel, pellicle, piece, plait, plank, plate, plating, ply, plywood,
   safety glass, scoop, scrap, scum, shard, shaving, sheet, shiver,
   shred, skin, slab, slat, slice, sliver, smithereen, snack, snatch,
   snip, snippet, splinter, stitch, stump, table, tablet, tatter,
   veneer, wafer