Someone who builds or repairs machinery, a technician; now specifically, someone who works with and repairs the mechanical parts of a motor vehicle, aircraft or similar.
A cheat who manipulates the cards or dice.
A manual worker; a labourer or artisan.
A hitman.
A device, command, or feature which allows someone to achieve a specific task.
An operative person or thing.
Any of a class of behaviors that produce consequences by operating (i.e., acting) upon the environment.
That operates to produce an effect.