life-and-death
1. Involving or pertaining to the risk or possibility that someone may die. (Used prenominally.) As a police officer in this neighborhood, you end up facing life-and-death situations on a regular basis.
2. Extremely serious or of dire consequences; of imperative importance. (Used prenominally.) We've got some life-and-death decisions to make at the next board meeting that will determine the fate of the company.
(a matter of) ˌlife and/or ˈdeath
(informal) used to describe a situation that is very important or serious: We need that business deal, it’s a matter of life or death to the company.It’s hardly a life-and-death decision whether we drive or take the train, is it?