When things impend, they are just about to happen. As you're heading into a haunted house, you might have the feeling that spooky noises and lurching monsters impend.
While you're more likely to see the adjective form of this word, impending, used to describe something that's looming or coming up in the future, you can also use the verb impend when something is approaching or developing. You could say, for example, that winter impends when the leaves have all fallen off the trees and the temperature has dropped. The Latin root is impendere, "hang over or be imminent," from pendere, or "hang."