supplementary
adj.adj. added to something else to improve it or provide more information. You use this for things like extra reading material or a second income.
adj. added to something else in order to complete or enhance it. Often used to describe materials, information, or payments that provide additional support to a primary source.
The teacher gave us supplementary exercises to practice at home.
The report includes supplementary data in the final pages to support the main findings.
While the primary text covers the historical events, the supplementary readings provide essential cultural context for understanding the motivations of the key figures involved.
From supplement + -ary; compare French supplémentaire.
Typically used attributively before a noun; often pairs with 'information', 'materials', or 'income'.