Operation.
Opportunity.
Opus.
Operative.
Operator.
A detective.
An operator's license, usually ops
Operation; action.
Method of operation.
Becoming full of a vegetable substance.
The incidental or subsidiary calculations performed in solving an overall problem.
A train movement.
Fermentation.
A place where work is carried on.
In paid employment.
Enough to allow one to use something.
Used in real life; practical.
Of or relating to employment.
That suffices but requires additional work.
That is or are functioning.