Are there Classical Latin words whose meanings are unknown to us?

1. What is the most famous Latin word?
2. Was classical Latin ever spoken?
3. How many classical Latin words are there?

What is the most famous Latin word?

Carpe diem.

Probably the most popular Latin phrase of modern times.

Was classical Latin ever spoken?

It is not possible to speak Latin as a native Roman of, e.g., the time of Caesar. Why is that? First, there are no native speakers of Latin. Latin, the language spoken in Ancient Rome, developed and changed over time until it turned into different languages, e.g., French, Italian, and Spanish.

How many classical Latin words are there?

Latin is a dead language. That's an advantage. In total, there are about 30,000 Latin words in classical writing, and I'll make a bet that we aren't finding a lot more where that came from.