There are a number of different synonyms that can be used to describe a two-propeller airplane. One such synonym might be a twin-engine aircraft, which is a more general term used to describe any plane that has two engines. Another term that could be used is a biplane, which is a specific type of aircraft that has two sets of wings stacked on top of each other. Finally, some people might refer to a two-propeller plane as a twin-prop, which is a shortened form of the term twin-propeller aircraft. Ultimately, the term you use to describe a two-propeller airplane will depend on the specific context in which you are discussing it.