obnubilate

Thanks to Naomi B for my favorite word of the week. It means to becloud or obscure something.

Example:

"It is the pity of the world, Dr. McAdam, to see a man of your parts obnubilate his mind with the juice of the grape."

--Patrick O'Brian

Distantly related to "nuance," of all things.

See Quinion's World Wide Words entry for more.