English Reference
adjective · noun

supplementary

adj. · n.
US /ˌsəpɫəˈmɛnɝi/ UK /sˌʌplɪmˈɛntəɹi/ sup·ple·men·tary UK spelling supplementaries

  1. 01 B2 Upper Intermediate Academic

    adj.added to something else to provide more information or to help complete it.

    adj.functioning as an addition to something else in order to complete it or provide further detail.

    Simple

    The teacher gave us supplementary reading to help us understand the history lesson.

    In context

    The report includes supplementary data in the appendices to support the primary findings presented in the executive summary.

    Usage

    Often used before a noun to describe materials, information, or income.

    Teacher's tip

    This is a common word in academic and formal contexts; students should use it instead of 'extra' when writing essays or business reports.

  2. 02 C1 Advanced Formal

    n.an extra part or thing that is added to something else.

    n.an item or amount provided as an addition to a standard or primary set.

    Simple

    The payment includes a small supplementary for the extra work performed.

    In context

    The budget allocated a significant supplementary for unforeseen maintenance costs during the winter quarter.

    Usage

    Less common than the adjective form; often refers to payments or specific document sections.

Usage supplementary material public · supplementary social · supplementary strong

When we offer supplementary food, such as seeds or meat scraps, this attracts birds of many different species in a combination and number that would not happen in nature.

ScienceDaily· 24 Aug 2026

From supplement + -ary; compare French supplémentaire.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level B2 · Upper Intermediate
Frequency Frequent
Updated