From Longman Business DictionaryRelated topics: Computersmission-criticalˈmission-ˌcritical adjectiveCOMPUTINGHUMAN RESOURCESmission-critical computersoftware and NETWORKs (=system of connected computers) are extremely important, allowing a business to be able to operateWithout mission-critical networks, virtually every aspect of the company’s international trade and commerce grinds to a halt.