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.