Supplementary angles are a pair of angles that add up to 180 degrees. They are commonly used in geometry to describe the relationship between two angles that are complementary to each other. There are several synonyms for the term "supplementary angles", such as "complementary angles", "opposite angles", and "explementary angles". Other related terms include "alternate angles", "corresponding angles", and "vertical angles". These terms are used to describe different types of angle relationships that can be observed in geometric figures. By understanding the different terms used to describe these angle relationships, students can develop a deeper understanding of geometry and its applications.