Other forms: supplemented, supplements, supplementing
A supplement is an extra dose of something missing from a diet. Vitamins, iron, fish oil in a capsule.
The word means an addition generally, so a newspaper supplement is the extra section that comes with the weekend paper, and a supplement on a bill is a surcharge. As a verb, stressed on the last syllable, it means to add to something insufficient, as in supplementing an income. The adjective supplementary appears in supplementary questions, which are the follow-ups after the first one.
1nounsupplementSomething taken or added to make up for a shortage.
“She takes an iron supplement every morning.”
2verborderTo add to something in order to improve or complete it.
“He supplemented his pension with evening work.”
A supplement fills a gap. Latin supplementum was whatever you added to make up a shortage, from supplēre, to fill up.
Latin
supplementum — that which is added to supply a shortage
English, today
supplement
Built from
From Latin supplementum (“that which is added to supply a shortage”), from supplere (“to provide something”).
Etymology from Wiktionary, CC BY-SA