margin of safety

Noun

 * 1)  The difference between the intrinsic value of a stock and its market price.
 * 2)  The strength of a business measured by the amount of income earned above the break-even point.
 * 3)  The difference between a therapeutic dose of a medication and a toxic dose.
 * 4)  The ratio of the strength of a structure to the requirements placed on that structure.