The term buffering refers to a process in which an agent, usually an acid or base, is added to a solution to prevent changes in pH. This helps maintain the stability and proper functioning of the system by resisting changes in acidity or alkalinity.
Many private nature reserves function as buffer zones for national parks, allowing for the free movement of species, so the parks do not become «biological islands». (arenalobservatorylodge.com)
Consider including a small percentage of buffer for unexpected school expenses excluded from your list. (financialwellness.org)