A composite type is:

A type comprised of other types
  • A type composed from at least one simple type
  • Another term for an Abstract Data Type
  • An instance of a class

A type with only 1 simple type is just a simple type. There is a better answer to this question.

An ADT is the realization of a data type, including the type and the operations allowed on the type.

An object is an instance of a class.