The Collaborative International Dictionary of English v.0.48:

Bedim \Be*dim"\ (b[-e]*d[i^]m"), v. t. [imp. & p. p. Bedimmed
   (b[-e]*d[i^]md"); p. pr. & vb. n. Bedimming.]
   To make dim; to obscure or darken. --Shak.
   [1913 Webster]