a matter of life or death

a matter of life or death

1. An issue or circumstance that involves or carries the possibility that someone may die. We have to get these donor organs to the hospital right away—it's a matter of life or death!
2. An extremely serious and important issue; a matter or circumstance that may have dire consequences. I hope you're well prepared, because this board meeting is a matter of life or death for the company.
See also: death, life, matter, of
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

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.
See also: and, life, matter, of
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

matter of life and death, a

An issue of vital importance. This term, used since the mid-nineteenth century, makes more sense as a matter of life or death, and indeed it sometimes is so used. An 1837 letter of Dickens states, “It is matter of life or death to us, to know whether you have got Ainsworth’s MS yet.” However, a life-and-death matter appears with equal frequency.
See also: and, life, matter, of
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer
See also: