* Noun: This is the most common usage. It refers to a significant change in the way something functions, especially a dramatic political or social upheaval.
* Example: "The French Revolution was a pivotal moment in European history."
* Verb: This is less common but possible, meaning to overthrow or completely change something.
* Example: "The company is trying to revolutionize the way we communicate."
* Adjective: This is even less common, but can be used to describe something that is revolutionary.
* Example: "The new technology was a revolutionary breakthrough."
Therefore, you need more context to determine the specific part of speech in your sentence.