hebetude

hebetude \HEB-uh-tood-; -tyood\, noun:

Mental dullness or sluggishness.

William Hazlitt considered Wordsworth's success an accident of history. "Had he lived in any other period ... he would never have been heard of. As it is, he has some difficulty to contend with the hebetude of his intellect."
-- Cristina Nehring, "The Gang: Coleridge, The Hutchinsons & The Wordsworths In 1802." (Review), American Scholar, June 22, 2001

Earlier on, when we merely democratized fame, we defended the right of any mouth-breather to rise from deserved obscurity on the strength of his God-given hebetude.
-- Florence King, "The misanthrope's corner", National Review, May 18, 1998

From that solitude, full of despair and terror, he was torn out brutally, with kicks and blows, passive, sunk in hebetude.
-- Joseph Conrad, Nostromo

Hebetude derives ultimately from Latin hebes, "blunt, dull, mentally dull, sluggish, stupid." The adjective form is hebetudinous.