Two-stroke engines have been commonly used in various types of machines such as motorcycles, boats, and power tools. If you are looking for synonyms of the word "two-stroke," you can consider using "two-cycle." The term "two-cycle" refers to an engine that completes an entire cycle of the combustion process in two strokes of the piston. Another synonym to consider is "two-cycle engine," which is often used interchangeably with "two-stroke." Additionally, you can use "two-stroke motor" or "two-cycle motor" as variations of the term. Overall, these synonyms effectively describe the same type of engine that has been widely used in many mechanical applications.