noun / verb
margin
MAR-jin/ˈmɑːrdʒɪn/
A space extending beyond the main boundary.
Wide blank margins separate the printed text from the page's edges.

Etymology
Latin margo meant an edge or border. On a written page, this became the bordering space between the text and the edge of the sheet.
In context
the printing press comes along and it becomes awkward to put these chevrons in the margin. So they migrate into the body of the text itself
More examples
- She writes reminders in the margin of her notebook.
- Our team leads by a margin of three points.
- The schedule leaves a small margin for unexpected delays.
Forms
margin · margins · margined · margining
marginal adjective — Located at or near an edge.