Back \Back\ (b[a^]k), n. [AS. b[ae]c, bac; akin to Icel., Sw., &
   LG. bak, Dan. bag; cf. OHG. bahho ham, Skr. bhaj to turn,
   OSlav. b[=e]g[u^] flight. Cf. {Bacon}.]
   1. In human beings, the hinder part of the body, extending
      from the neck to the end of the spine; in other animals,
      that part of the body which corresponds most nearly to
      such part of a human being; as, the back of a horse, fish,
      or lobster.
      
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   2. An extended upper part, as of a mountain or ridge.
      
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            [The mountains] their broad bare backs upheave
            Into the clouds.                      --Milton.
      
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   3. The outward or upper part of a thing, as opposed to the
      inner or lower part; as, the back of the hand, the back of
      the foot, the back of a hand rail.
      
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            Methought Love pitying me, when he saw this,
            Gave me your hands, the backs and palms to kiss.
                                                  --Donne.
      
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   4. The part opposed to the front; the hinder or rear part of
      a thing; as, the back of a book; the back of an army; the
      back of a chimney.
      
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   5. The part opposite to, or most remote from, that which
      fronts the speaker or actor; or the part out of sight, or
      not generally seen; as, the back of an island, of a hill,
      or of a village.
      
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   6. The part of a cutting tool on the opposite side from its
      edge; as, the back of a knife, or of a saw.
      
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   7. A support or resource in reserve.
      
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            This project
            Should have a back or second, that might hold,
            If this should blast in proof.        --Shak.
      
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   8. (Naut.) The keel and keelson of a ship.
      
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   9. (Mining) The upper part of a lode, or the roof of a
      horizontal underground passage.
      
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   10. A garment for the back; hence, clothing. [Obs.]
       
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             A bak to walken inne by daylight.    --Chaucer.
       
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   {Behind ones back}, when one is absent; without one's
      knowledge; as, to ridicule a person behind his back.

   {Full back}, {Half back}, {Quarter back} (Football), players
      stationed behind those in the front line.

   {To be on ones back} or {To lie on ones back}, to be
      helpless.

   {To put ones back up} or {to get ones back up}, to assume
      an attitude of obstinate resistance (from the action of a
      cat when attacked). [Colloq.]

   {To see the back of}, to get rid of.

   {To turn the back}, to go away; to flee.

   {To turn the back on one}, to forsake or neglect him.
      
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