The Collaborative International Dictionary of English v.0.48:

Blank \Blank\, v. t. [imp. & p. p. Blanked; p. pr. & vb. n.
   Blanking.] [Cf. 3d Blanch.]
   1. To make void; to annul. [Obs.] --Spenser.
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   2. To blanch; to make blank; to damp the spirits of; to
      dispirit or confuse. [Obs.]
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            Each opposite that blanks the face of joy. --Shak.
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