matter of life and death, a
A very urgent issue, situation, or circumstance. This expression can be used either literally, as in She told the doctor to hurry as it was a matter of life and death, or hyperbolically, as in Don't worry about finishing on time—it's hardly a matter of life and death. First recorded in 1849, it alludes to such urgency that someone's life depends on it. Although a matter of life or death would make more sense, it is rarely put that way.
Words nearby matter of life and death, a
matter of course,
matter of course, a,
matter of fact,
matter of fact, a,
matter of law,
matter of life and death, a,
matter of opinion,
matter of opinion, a,
matter of record,
matter wave,
matter waves