Origin: Latin suffix -ary
Supplementary has 4 different meanings across 1 category:
Something additional; an extra.
"The teacher handed out supplementary worksheets to help students who needed more practice on fractions."
In plain English: A supplementary item is an extra thing added to something else to make it more complete.
"The supplementary to his salary helped him pay off his debts."
functioning in a supporting capacity
"the main library and its auxiliary branches"
added to complete or make up a deficiency
"produced supplementary volumes"
Additional; added to supply what is wanted.
"The supplementary lesson was added to help students catch up on the missed material."
In plain English: Supplementary means something that is added to help complete or improve what already exists.
"The course offered supplementary lessons to help students review their notes before the exam."
Usage: Use supplementary when something is provided as an addition or supplement, such as in the phrase "supplementary materials." This term emphasizes that the item fills a gap rather than replacing existing content.
The word supplementary comes from the Latin root supplementum, meaning something added to make up a deficiency, combined with the suffix -ary. It entered English through French as an adjective describing material that completes or enhances what already exists.