The Collaborative International Dictionary of English v.0.48:

Blow \Blow\, n. [OE. blaw, blowe; cf. OHG. bliuwan, pliuwan, to
   beat, G. bl[aum]uen, Goth. bliggwan.]
   1. A forcible stroke with the hand, fist, or some instrument,
      as a rod, a club, an ax, or a sword.
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            Well struck ! there was blow for blow. --Shak.
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   2. A sudden or forcible act or effort; an assault.
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            A vigorous blow might win [Hanno's camp]. --T.
                                                  Arnold.
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   3. The infliction of evil; a sudden calamity; something which
      produces mental, physical, or financial suffering or loss
      (esp. when sudden); a buffet.
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            A most poor man, made tame to fortune's blows.
                                                  --Shak.
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   At a blow, suddenly; at one effort; by a single vigorous
      act. "They lose a province at a blow." --Dryden.

   To come to blows, to engage in combat; to fight; -- said of
      individuals, armies, and nations.
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   Syn: Stroke; knock; shock; misfortune.
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