Common Words:
* Operate: To work or function
* Operation: The act of working or functioning
* Operator: A person who works a machine or device
* Cooperate: To work together with others
* Operate: To perform a surgical procedure
* Operative: Relating to or involved in an operation
Less Common Words:
* Opera: A dramatic work in which the dialogue is sung (from the Italian "opere" which means "works")
* Operetta: A light opera
* Operable: Capable of being operated on or worked
* Operate: To make something work or function
* Operative: A secret agent or spy
You can also find the root "oper" in many compound words:
* Superoperate: To operate above or beyond
* Counteroperate: To work against or in opposition to
* Interoperate: To work together or in cooperation
Let me know if you'd like to explore any of these words in more detail!