What does the Greek word vapor mean?

The Greek word for "vapor" is ἀτμός (atmos). It's related to the English word "atmosphere."

Here's a breakdown:

* ἀτμός (atmos): vapor, steam, mist, breath, air, atmosphere

The word "atmos" has a broader meaning than just "vapor" in English. It encompasses the idea of a subtle, intangible substance that surrounds us. This is why it's also used for "atmosphere."