Maximum Allowable Downtime (MAD)

 Definition(s):

The absolute maximum time that the system can be unavailable without direct or indirect ramifications to the organization.

 Source: BCM Institute

The maximum time a business can tolerate the absence or unavailability of a particular business function.

 Source: TechTarget

The maximum time a business can tolerate an application, process or system being unavailable before having a detrimental impact to the organization.

 Source: Erwood Group