When you’re thunderstruck, you’re dumbfounded by something. Only something very shocking can leave you thunderstruck. If you walk by a statue in the park and it starts talking to you, you’ll probably be thunderstruck.
If you were struck by lightning, it would stop you in your tracks. That unlikely event is the inspiration for this word, which involves more of a shock to the mind. When you’re thunderstruck, you’re amazed and stunned. The news that you’re pregnant could leave you thunderstruck. An incredible news story could leave you thunderstruck. This is a strong word for when your mind is truly blown.