In C#, an anonymous object is an object that is defined without an explicit class or type name. Instead, its properties are defined inline using a special syntax. Anonymous objects are typically used for creating objects with a small number of properties for use in local scope, such as in LINQ queries or when returning data from a method.

Here's an example of how to create an anonymous object in C#: 

Note that anonymous objects are read-only and their properties cannot be modified after they are created. Also, because anonymous objects are implicitly typed, you cannot use them as return types or parameters in method signatures. If you need to define a type with properties that can be used across multiple methods or classes, you should define a custom class or struct instead of using an anonymous object.