worth so many years purchase

Purchase \Pur"chase\ (?; 48), n. [OE. purchds, F. pourchas eager
   pursuit. See {Purchase}, v. t.]
   1. The act of seeking, getting, or obtaining anything. [Obs.]
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            I'll . . . get meat to have thee,
            Or lose my life in the purchase.      --Beau. & Fl.
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   2. The act of seeking and acquiring property.
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   3. The acquisition of title to, or properly in, anything for
      a price; buying for money or its equivalent.
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            It is foolish to lay out money in the purchase of
            repentance.                           --Franklin.
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   4. That which is obtained, got, or acquired, in any manner,
      honestly or dishonestly; property; possession;
      acquisition. --Chaucer. B. Jonson.
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            We met with little purchase upon this coast, except
            two small vessels of Golconda.        --De Foe.
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            A beauty-waning and distressed widow . . .
            Made prize and purchase of his lustful eye. --Shak.
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   5. That which is obtained for a price in money or its
      equivalent. "The scrip was complete evidence of his right
      in the purchase." --Wheaton.
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   6. Any mechanical hold, or advantage, applied to the raising
      or removing of heavy bodies, as by a lever, a tackle,
      capstan, and the like; also, the apparatus, tackle, or
      device by which the advantage is gained.
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            A politician, to do great things, looks for a power
            -- what our workmen call a purchase.  --Burke.
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   7. (Law) Acquisition of lands or tenements by other means
      than descent or inheritance, namely, by one's own act or
      agreement. --Blackstone.
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   {Purchase criminal}, robbery. [Obs.] --Spenser.

   {Purchase money}, the money paid, or contracted to be paid,
      for anything bought. --Berkeley.

   {Worth [so many] years' purchase}, or {At [so many] years'
   purchase}, a phrase by which the value or cost of a thing is
      expressed in the length of time required for the income to
      amount to the purchasing price; as, he bought the estate
      at a twenty years' purchase. To say one's life is

   {not worth a day's purchase} in the same as saying one will
      not live a day, or is in imminent peril.
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