Looking for word to describe something extremely rare, specifically lightning striking twice. Is there any word for this?
If you're looking for an idiomatic way to say this, you've hit the nail on the head!
Lightning doesn't strike twice.
Often is used to say that it's unlikely that the same thing will happen again. Def.
Other suitable phrases are:
- Chance Event
- Freak Occurrence (as @Smock mentioned)
Please note, these aren't entirely interchangeable, so it is worth looking them up to make sure you are using the best one for the situation you're trying to describe.