Is it bad to not know what ICU means?

It's not uncommon for people not to know what ICU means, and even more common for people not to know what it means.

After all, the acronym "Intensive Care Unit" is not common knowledge, so it's not unusual for people other than professional practitioners or native speakers to not know what it means.

But if you say "Intensive Care Unit" or "ICU," no one will know what it means.

The reason the term ICU has become more widely known in recent years is because of media outlets such as hospital dramas (e.g., Springtime in the ER, The White Tower, etc.).