The Collaborative International Dictionary of English v.0.48:

Sheet \Sheet\, n. [OE. shete, schete, AS. sc[=e]te, sc[=y]te,
   fr. sce['a]t a projecting corner, a fold in a garment (akin
   to D. schoot sheet, bosom, lap, G. schoss bosom, lap, flap of
   a coat, Icel. skaut, Goth. skauts the hem of a garment);
   originally, that which shoots out, from the root of AS.
   sce['o]tan to shoot. [root]159. See Shoot, v. t.]
   In general, a large, broad piece of anything thin, as paper,
   cloth, etc.; a broad, thin portion of any substance; an
   expanded superficies. Specifically:
   (a) A broad piece of cloth, usually linen or cotton, used for
       wrapping the body or for a covering; especially, one used
       as an article of bedding next to the body.
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             He fell into a trance, and saw heaven opened, and a
             certain vessel descending unto him, as it had been
             a great sheet knit at the four corners. --Acts x.
                                                  10, 11.
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             If I do die before thee, prithee, shroud me
             In one of those same sheets.         --Shak.
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   (b) A broad piece of paper, whether folded or unfolded,
       whether blank or written or printed upon; hence, a
       letter; a newspaper, etc.
   (c) A single signature of a book or a pamphlet; in pl., the
       book itself.
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             To this the following sheets are intended for a
             full and distinct answer.            --Waterland.
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   (d) A broad, thinly expanded portion of metal or other
       substance; as, a sheet of copper, of glass, or the like;
       a plate; a leaf.
   (e) A broad expanse of water, or the like. "The two beautiful
       sheets of water." --Macaulay.
   (f) A sail. --Dryden.
   (g) (Geol.) An extensive bed of an eruptive rock intruded
       between, or overlying, other strata.
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   2. [AS. sce['a]ta. See the Etymology above.] (Naut.)
      (a) A rope or chain which regulates the angle of
          adjustment of a sail in relation in relation to the
          wind; -- usually attached to the lower corner of a
          sail, or to a yard or a boom.
      (b) pl. The space in the forward or the after part of a
          boat where there are no rowers; as, fore sheets; stern
          sheets.
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   Note: Sheet is often used adjectively, or in combination, to
         denote that the substance to the name of which it is
         prefixed is in the form of sheets, or thin plates or
         leaves; as, sheet brass, or sheet-brass; sheet glass,
         or sheet-glass; sheet gold, or sheet-gold; sheet iron,
         or sheet-iron, etc.
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   A sheet in the wind, half drunk. [Sailors' Slang]

   Both sheets in the wind, very drunk. [Sailors' Slang]

   In sheets, lying flat or expanded; not folded, or folded
      but not bound; -- said especially of printed sheets.

   Sheet bend (Naut.), a bend or hitch used for temporarily
      fastening a rope to the bight of another rope or to an
      eye.

   Sheet lightning, Sheet piling, etc. See under
      Lightning, Piling, etc.
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The Collaborative International Dictionary of English v.0.48:

Lightning \Light"ning\ (l[imac]t"n[i^]ng), n. [For lightening,
   fr. lighten to flash.]
   1. A discharge of atmospheric electricity, accompanied by a
      vivid flash of light, commonly from one cloud to another,
      sometimes from a cloud to the earth. The sound produced by
      the electricity in passing rapidly through the atmosphere
      constitutes thunder.
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   2. The act of making bright, or the state of being made
      bright; enlightenment; brightening, as of the mental
      powers. [R.]
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   Ball lightning, a rare form of lightning sometimes seen as
      a globe of fire moving from the clouds to the earth.

   Chain lightning, lightning in angular, zigzag, or forked
      flashes.

   Heat lightning, more or less vivid and extensive flashes of
      electric light, without thunder, seen near the horizon,
      esp. at the close of a hot day.

   Lightning arrester (Telegraphy), a device, at the place
      where a wire enters a building, for preventing injury by
      lightning to an operator or instrument. It consists of a
      short circuit to the ground interrupted by a thin
      nonconductor over which lightning jumps. Called also
      lightning discharger.

   Lightning bug (Zool.), a luminous beetle. See Firefly.

   Lightning conductor, a lightning rod.

   Lightning glance, a quick, penetrating glance of a
      brilliant eye.

   Lightning rod, a metallic rod set up on a building, or on
      the mast of a vessel, and connected with the earth or
      water below, for the purpose of protecting the building or
      vessel from lightning.

   Sheet lightning, a diffused glow of electric light flashing
      out from the clouds, and illumining their outlines. The
      appearance is sometimes due to the reflection of light
      from distant flashes of lightning by the nearer clouds.
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