Benighted is an adjective that means in a state of intellectual or moral ignorance. 

The Old English word benight was a verb that meant ‘to obscure’ or ‘to cover in the darkness of night.’ When something is benighted it is ‘in the dark,’ if you will. Our word of the day is used to describe someone who is ‘in the dark’ in the sense of being ignorant or unaware. Here’s an example:

While the rest of us immediately got the joke Rachel told, William remained benighted for hours. Some guys are just destined to be in the dark when it comes to understanding sophisticated humor.