The Collaborative International Dictionary of English v.0.48:

Dwale \Dwale\, n. [OE. dwale, dwole, deception, deadly
   nightshade, AS. dwala, dwola, error, doubt; akin to E. dull.
   See Dull, a.]
   1. (Bot.) The deadly nightshade (Atropa Belladonna), having
      stupefying qualities.
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   2. (Her.) The tincture sable or black when blazoned according
      to the fantastic system in which plants are substituted
      for the tinctures.
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   3. A sleeping potion; an opiate. --Chaucer.
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