From katanusso; a prickling (sensation, as of the limbs asleep), i.e. (by implication, (perhaps by some confusion with neuo or even with nux)) stupor (lethargy) -- slumber.
KJV: (According as it is written, God hath given them the spirit of slumber, eyes that they should not see, and ears that they should not hear;) unto this day.
NASB: just as it is written, "GOD GAVE THEM A SPIRIT OF STUPOR, EYES TO SEE NOT AND EARS TO HEAR NOT, DOWN TO THIS VERY DAY."