to spring upon

Spring \Spring\ (spr[i^]ng), v. i. [imp. {Sprang} (spr[a^]ng) or
   {Sprung} (spr[u^]ng); p. p. {Sprung}; p. pr. & vb. n.
   {Springing}.] [AS. springan; akin to D. & G. springen, OS. &
   OHG. springan, Icel. & Sw. springa, Dan. springe; cf. Gr.
   spe`rchesqai to hasten. Cf. {Springe}, {Sprinkle}.]
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   1. To leap; to bound; to jump.
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            The mountain stag that springs
            From height to height, and bounds along the plains.
                                                  --Philips.
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   2. To issue with speed and violence; to move with activity;
      to dart; to shoot.
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            And sudden light
            Sprung through the vaulted roof.      --Dryden.
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   3. To start or rise suddenly, as from a covert.
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            Watchful as fowlers when their game will spring.
                                                  --Otway.
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   4. To fly back; as, a bow, when bent, springs back by its
      elastic power.
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   5. To bend from a straight direction or plane surface; to
      become warped; as, a piece of timber, or a plank,
      sometimes springs in seasoning.
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   6. To shoot up, out, or forth; to come to the light; to begin
      to appear; to emerge; as a plant from its seed, as streams
      from their source, and the like; -- often followed by up,
      forth, or out.
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            Till well nigh the day began to spring. --Chaucer.
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            To satisfy the desolate and waste ground, and to
            cause the bud of the tender herb to spring forth.
                                                  --Job xxxviii.
                                                  27.
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            Do not blast my springing hopes.      --Rowe.
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            O, spring to light; auspicious Babe, be born.
                                                  --Pope.
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   7. To issue or proceed, as from a parent or ancestor; to
      result, as from a cause, motive, reason, or principle.
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            [They found] new hope to spring
            Out of despair, joy, but with fear yet linked.
                                                  --Milton.
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   8. To grow; to thrive; to prosper.
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            What makes all this, but Jupiter the king,
            At whose command we perish, and we spring? --Dryden.
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   {To spring at}, to leap toward; to attempt to reach by a
      leap.

   {To spring forth}, to leap out; to rush out.

   {To spring in}, to rush in; to enter with a leap or in haste.
      

   {To spring on} or {To spring upon}, to leap on; to rush on
      with haste or violence; to assault.
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