revolutionary

If something is revolutionary, it causes great change.

Example: Alexander Fleming's discovery of penicillin was revolutionary.

If something is revolutionary, it is relating to a revolution: a war against a government by its country's own people.

Example: The people were filled with revolutionary fervor.

A revolutionary is a person who is involved in a revolution or who wants a revolution to happen.

Example: Many of the revolutionaries were arrested and put on trial.