noun

1. something added, esp. to make up for a lack or deficiency
2. a section added to a book or the like to give additional information, correct errors in the body of the work, etc.
3. ☆ a separate section containing feature stories, comic strips, or the like, issued with a newspaper
4. the amount to be added to a given angle or arc to make 180° or a semicircle

Etymology: ME < L supplementum < supplere: see supply

transitive verb