The term "supplementary" refers to something that is additional or extra, and which complements or enhances what already exists. It can be used in a variety of contexts, such as education where it may refer to materials or resources provided to students to support their learning, or in nutrition where it describes foods or substances taken to provide additional nutrients beyond those obtained from regular meals. In general, the word "supplementary" suggests something that is extra or optional, but can also be essential for completing a task or achieving a goal.