Meaning : Process or manner of functioning or operating.
Example :
The power of its engine determines its operation.
The plane's operation in high winds.
They compared the cooking performance of each oven.
The jet's performance conformed to high standards.
Synonyms : operation, performance
Meaning : Performing or able to perform its regular function.
Example :
A functioning flashlight.
Not performing or able to perform its regular function.
A malfunctioning valve.