Source : Webster's Revised Unabridged Dictionary (1913)

Dead \Dead\ (d[e^]d), a. [OE. ded, dead, deed, AS. de['a]d; akin
   to OS. d[=o]d, D. dood, G. todt, tot, Icel. dau[eth]r, Sw. &
   Dan. d["o]d, Goth. daubs; prop. p. p. of an old verb meaning
   to die. See {Die}, and cf. {Death}.]
   1. Deprived of life; -- opposed to {alive} and {living};
      reduced to that state of a being in which the organs of
      motion and life have irrevocably ceased to perform their
      functions; as, a dead tree; a dead man. ``The queen, my
      lord, is dead.'' --Shak.

            The crew, all except himself, were dead of hunger.
                                                  --Arbuthnot.

            Seek him with candle, bring him dead or living.
                                                  --Shak.

   2. Destitute of life; inanimate; as, dead matter.

   3. Resembling death in appearance or quality; without show of
      life; deathlike; as, a dead sleep.

   4. Still as death; motionless; inactive; useless; as, dead
      calm; a dead load or weight.

   5. So constructed as not to transmit sound; soundless; as, a
      dead floor.

   6. Unproductive; bringing no gain; unprofitable; as, dead
      capital; dead stock in trade.

   7. Lacking spirit; dull; lusterless; cheerless; as, dead eye;
      dead fire; dead color, etc.

   8. Monotonous or unvaried; as, a dead level or pain; a dead
      wall. ``The ground is a dead flat.'' --C. Reade.

   9. Sure as death; unerring; fixed; complete; as, a dead shot;
      a dead certainty.

            I had them a dead bargain.            --Goldsmith.

   10. Bringing death; deadly. --Shak.

   11. Wanting in religious spirit and vitality; as, dead faith;
       dead works. ``Dead in trespasses.'' --Eph. ii. 1.

   12. (Paint.)
       (a) Flat; without gloss; -- said of painting which has
           been applied purposely to have this effect.
       (b) Not brilliant; not rich; thus, brown is a dead color,
           as compared with crimson.

   13. (Law) Cut off from the rights of a citizen; deprived of
       the power of enjoying the rights of property; as, one
       banished or becoming a monk is civilly dead.

   14. (Mach.) Not imparting motion or power; as, the dead
       spindle of a lathe, etc. See {Spindle}.

   {Dead ahead} (Naut.), directly ahead; -- said of a ship or
      any object, esp. of the wind when blowing from that point
      toward which a vessel would go.

   {Dead angle} (Mil.), an angle or space which can not be seen
      or defended from behind the parapet.

   {Dead block}, either of two wooden or iron blocks intended to
      serve instead of buffers at the end of a freight car.

   {Dead calm} (Naut.), no wind at all.

   {Dead center}, or {Dead point} (Mach.), either of two points
      in the orbit of a crank, at which the crank and connecting
      rod lie a straight line. It corresponds to the end of a
      stroke; as, A and B are dead centers of the crank
      mechanism in which the crank C drives, or is driven by,
      the lever L.

   {Dead color} (Paint.), a color which has no gloss upon it.

   {Dead coloring} (Oil paint.), the layer of colors, the
      preparation for what is to follow. In modern painting this
      is usually in monochrome.

   {Dead door} (Shipbuilding), a storm shutter fitted to the
      outside of the quarter-gallery door.

   {Dead flat} (Naut.), the widest or midship frame.

   {Dead freight} (Mar. Law), a sum of money paid by a person
      who charters a whole vessel but fails to make out a full
      cargo. The payment is made for the unoccupied capacity.
      --Abbott.

   {Dead ground} (Mining), the portion of a vein in which there
      is no ore.

   {Dead hand}, a hand that can not alienate, as of a person
      civilly dead. ``Serfs held in dead hand.'' --Morley. See
      {Mortmain}.

   {Dead head} (Naut.), a rough block of wood used as an anchor
      buoy.

   {Dead heat}, a heat or course between two or more race
      horses, boats, etc., in which they come out exactly equal,
      so that neither wins.

   {Dead horse}, an expression applied to a debt for wages paid
      in advance. [Law]

   {Dead language}, a language which is no longer spoken or in
      common use by a people, and is known only in writings, as
      the Hebrew, Greek, and Latin.

Source : WordNet®

dead ahead
     adv : exactly ahead or in front; "the laboratory is dead ahead"