The Collaborative International Dictionary of English v.0.48:

Forestall \Fore*stall"\, v. t. [imp. & p. p. Forestalled; p.
   pr. & vb. n. Forestalling.] [OE. forstallen to stop, to
   obstruct; to stop (goods) on the way to the market by buying
   them beforehand, from forstal obstruction, AS. forsteal,
   foresteall, prop., a placing one's self before another. See
   Fore, and Stall.]
   1. To take beforehand, or in advance; to anticipate.
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            What need a man forestall his date of grief,
            And run to meet what he would most avoid? --Milton.
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   2. To take possession of, in advance of some one or something
      else, to the exclusion or detriment of the latter; to get
      ahead of; to preoccupy; also, to exclude, hinder, or
      prevent, by prior occupation, or by measures taken in
      advance.
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            An ugly serpent which forestalled their way.
                                                  --Fairfax.
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            But evermore those damsels did forestall
            Their furious encounter.              --Spenser.
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            To be forestalled ere we come to fall. --Shak.
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            Habit is a forestalled and obstinate judge. --Rush.
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   3. To deprive; -- with of. [R.]
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            All the better; may
            This night forestall him of the coming day! --Shak.
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   4. (Eng. Law) To obstruct or stop up, as a way; to stop the
      passage of on highway; to intercept on the road, as goods
      on the way to market.
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   To forestall the market, to buy or contract for merchandise
      or provision on its way to market, with the intention of
      selling it again at a higher price; to dissuade persons
      from bringing their goods or provisions there; or to
      persuade them to enhance the price when there. This was an
      offense at law in England until 1844. --Burrill.

   Syn: To anticipate; monopolize; engross.
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