* Servitude: This is a general term for the state of being a servant or slave, encompassing the conditions of being a serf.
* Peonage: This specifically refers to a system of forced labor, often tied to debt, which is reminiscent of serfdom.
* Bondage: This refers to the state of being bound or restrained, capturing the limited freedom of a serf.
* Feudalism: While not directly an abstract noun for "serf", this system of social and political organization is inherently tied to the concept of serfdom.
* Dependence: This refers to the state of relying on someone else for support, which is a key aspect of serfdom.
Ultimately, the best abstract noun for "serf" depends on the specific context and the nuance you want to emphasize.