It's used in many words related to time, such as:
* Chronology: The order in which events happen.
* Chronometer: A device for measuring time precisely.
* Chronic: Lasting for a long time.
* Synchronize: To happen at the same time.
* Chronograph: A device that measures time intervals.
So, whenever you see the word "chrono" in a word, you can usually assume it has something to do with time.