Other forms: binders
A binder is a stiff cover with rings that holds punched pages. A ring binder, a lever-arch binder, put it in the binder.
The two-ring British standard and the three-ring American one are not compatible, which is why paper bought in one country will not fit a binder from the other. In cooking a binder is an ingredient like egg that holds a mixture together.
1nounbinderA stiff cover with rings that holds punched pages.
“He kept all his lecture notes in a blue ring binder.”
binder is a folder.
Bind plus -er. Bind comes from Old English bindan, and a binder was first a person who bound books.
Middle English
byndere
English, today
binder
From Middle English byndere; equivalent to bind + -er.
Etymology from Wiktionary, CC BY-SA