A synonym for "object-oriented programming" is OOP, which refers to a programming paradigm that is centered around creating objects to store data and functions. Another synonym is "class-based programming," which specifically refers to the use of classes to create objects. Some other related terms include "inheritance," which refers to the ability of objects to inherit properties and methods from parent objects; "polymorphism," which refers to the ability of objects to take on multiple forms and behave differently depending on the context; and "encapsulation," which refers to the practice of hiding implementation details of objects and only exposing necessary information. Overall, object-oriented programming is a powerful and versatile approach to software development that allows programmers to create complex systems using modular, reusable components.