To smite is to strike with a heavy blow. If you’re playing an ancient Norse warrior in a play, you might get to smite your enemy with a club.
Smite comes from the old English for striking or smearing. You’re most likely to find it reading Biblical stories or mythologies, for example, where the thunderbolt of Zeus smites some misbehaving Greek fellow. The past participle of this verb is the cool word smitten, which is what you say about someone who's fallen head over heels for something or someone, that is, their emotions have been struck.