A more thorough explanation:

Definition: Coterellus (pronounced kot-uh-rel-uhs) is a term from Law Latin that refers to a serf who lives in a cottage. They are a servile tenant whose person, issue, and goods are at the disposal of the lord.

For example, in medieval times, a coterellus would have been a person who lived in a small cottage on a lord's estate and worked the land. They would have been considered a lower class of people and would have had very little control over their own lives.

It is important to note that a coterellus was different from a cotarius, who had free socage tenure and paid a stated firm (rent) in provisions or money, with some occasional customary service. The coterellus, on the other hand, held in mere villenage and had their person, issue, and goods disposed of at the pleasure of the lord.

Overall, coterellus is a term that describes a type of tenant who was considered to be of a lower class and had very little control over their own lives.