Question

What was the Diet of worms For Martin Luther??

Answer 1

It meant this:
Diet of Worms, meeting of the Diet (assembly) of the Holy Roman Empire held at Worms, Germany, in 1521, made famous by Martin Luther's appearance before it to respond to charges of heresy.

Answer 2

The Diet of Worms:  a formal  assembly of the whole Empire, the Empire being the Holy Roman Empire (HRR). Worms is a city in present day Germany.