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.
A similar agricultural labourer in 18th and 19th century Europe.
A partially free peasant of a low hereditary class, attached like a slave to the land owned by a feudal lord and required to perform labour, enjoying minimal legal or customary rights.
A worker unit.