The Collaborative International Dictionary of English v.0.48:

Obnubilate \Ob*nu"bi*late\, v. t. [L. obnubilatus, p. p. of
   obnubilare to obscure. See Ob-, and Nubilate.]
   To cloud; to obscure. [Obs.] --Burton. -- Ob*nu"bi*la"tion,
   n. [Obs.] --Beddoes.
   [1913 Webster]