The word "cotter" has two main meanings:
As a Fastener: You would use "cotter" when discussing tools, machinery, or construction. For example, if you were assembling furniture, you might say, "Make sure to use a cotter to secure the legs of the table."
As a Peasant: When talking about history or social classes, you could say, "The cotters in medieval Scotland worked hard to cultivate their small plots of land."
In technical discussions, you might hear phrases like "cotter pin," which is a specific type of cotter used to secure fasteners in place. In historical discussions, you could use "cotter" in contexts discussing feudal systems or the social hierarchy of medieval societies.
While the two main meanings above are the most common, the term "cotter" is not widely used in everyday conversation outside of specific contexts such as mechanics or history.
The word "cotter" doesn't have specific idioms or phrasal verbs associated with it. However, it can be part of phrases in technical contexts (like "install a cotter pin") or historical discussions.
To sum up, a cotter can either refer to a small device that holds things together or a peasant farmer from medieval times.