Operation.
Opportunity.
Opus.
Operative.
Operator.
A detective.
An operator's license, usually ops
A surgical operation.
A particular method for performing a task.
The steps taken in an action or other legal proceeding.
A series of small tasks or steps taken to accomplish an end.
A subroutine or function coded to perform a specific task, but does not return a value.
The set of established forms or methods of an organized body for accomplishing a certain task or tasks.