noun
overlap width; pasting margin
Literal sense: the extra width left on paper or cloth for gluing pieces together. Common in crafts, bookbinding, and packaging.
封筒を作るときは、糊代を1センチほど取ってください。
When making an envelope, leave a pasting margin of about 1 cm.
noun
Figurative extension: room to maneuver, flexibility, or a buffer in plans, schedules, or budgets. Often used in business and everyday conversation.
スケジュールに糊代を持たせておくと、急な変更にも対応できる。
If you build some leeway into the schedule, you can handle sudden changes.
予算には少し糊代が必要だ。
We need a little allowance in the budget.
余裕 is a more general word for surplus, composure, or room to spare, while 糊代 specifically implies a deliberate margin or buffer, often with a nuance of planning.
マージン is a loanword used in finance and printing, similar to the figurative sense of 糊代, but 糊代 has a more concrete, craft-related origin.
Compound of 糊 (のり, 'paste') and 代 (しろ, 'margin' or 'allowance'). Originally referred to the overlapping part of paper or cloth for gluing, later extended metaphorically to any kind of buffer or leeway.