What is another word for operation?

The best alternative word for "operation" depends on the context. Here are some options:

For medical procedures:

* Surgery

* Procedure

* Treatment

* Intervention

* Process

For business and military contexts:

* Action

* Task

* Mission

* Project

* Undertaking

For general use:

* Activity

* Function

* Process

* Action

* Work

For specific types of operations:

* Campaign (marketing, political)

* Deployment (military)

* Execution (plan)

* Implementation (plan)

To give you the most accurate replacement, please provide more context about what kind of operation you're referring to.