Servitor was a term for various kinds of automated mechanical entities. They had countless military and civilian applications, often replacing humans in dangerous, menial, or repetitive tasks. Possessing variable levels of intelligence, they were almost always designed to lack self-awareness, as it was deemed far too cruel to create a sentient being without allowing it free will.
After the Melding Plague on Yellowstone, possessing servitors in Chasm City -- even older models which would appear decrepit next to their plague-susceptible descendants -- was seen as a sign of wealth.
The moral restriction against creating intelligent servitors was violated by the Conjoiner, Skade, without the knowledge of the greater Mother Nest, or even the Inner Sanctum. After becoming aware of the threat of the Inhibitors, and perhaps after being influence by The Mademoiselle, she decided to create a fleet of lighthuggers. However, she did not trust the overseeing of their clandestine construction to even her fellow conjoined, and so created the Master of Works to coordinate the asteroid-factory.