What does the greek root thet mean?

There is no Greek root "thet." It's possible you are thinking of a different root, or perhaps there's a typo. Could you please double-check the spelling or provide more context?

For example, are you thinking of:

* θε- (the-) This is a Greek prefix that means "put" or "place." Examples include:

* θέατρον (theatron): "theater" (literally, "place of seeing")

* θέσις (thesis): "position," "place," "argument"

* θεός (theos): "god"

* θερμός (thermos): "hot"

If you could give me more information, I can help you find the correct Greek root.