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.