If - dict can mean relating to words, explain why it is in the word dictator.

This is just my guess, but maybe it's because the dictators use their words to climb up and become one?

For example, Adolf Hitler was in the congress for a long time before he became a dictator. He talked and gave lots of speeches that the Germans (At the time) thought were good, so they slowly trusted him and unfortunately let him become dictator.

I wouldn't use this as an answer to a quiz or test, though.