I always tried to avoid the use of the word punishment, just my thoughts. In my childhood - I equated punishment with "I was bad".

For my boys, I tried to use words like thinking time or taking a break to calm down or just plain time out.

If they asked why, I explained that their behavior was not safe, hurtful, etc.

I tried really hard to reiterate that they were not bad, their behavior was not okay (or something along those lines)

After time out, I always made sure to tell them that I still loved them and that everybody makes mistakes and tried to get them to let me know what led up to the behavior so we could come up with better ideas for the next time...