What is a greek word in the English language?

Many Greek words are in the English language. It depends on what you mean by "in". Do you mean words directly derived or words with roots that come from Greek?

Here are a few examples showing different levels of Greek influence:

* Directly derived: Chaos, crisis, democracy, philosophy, phone, psyche. These retain significant resemblance to their Greek origins.

* With Greek roots: Television (tele- meaning "far" and -vision meaning "seeing"), Biology (bio- meaning "life" and -logy meaning "study of"), Astronomy (astro- meaning "star" and -nomy meaning "law" or "study of"). These are more heavily Anglicized but retain recognizable Greek components.

So there isn't one single answer; hundreds, if not thousands, of words in English have Greek origins, to varying degrees.