Life-sustaining

adj.kind, resilientprofessional

What it means

Necessary for preserving life or essential bodily function.

Reach for it when describing material support whose interruption would threaten survival, not merely comfort

Solar batteries kept life-sustaining equipment running through the outage.

everyday
essential
the item cannot safely be omitted
not when Essential applies to any important purpose and does not identify life as the stake.
everyday
vital
something is essential to continued life or success
not when Vital is broader and often figurative, while life-sustaining makes the survival claim explicit.
warm
nourishing
food or care supplies what healthy growth requires
not when Nourishing suggests positive development rather than minimum survival.
professional
lifesaving
an intervention prevents an imminent or probable death
not when Lifesaving describes rescue from danger; ongoing support may instead sustain a stable life.
formal
life-supporting
conditions or systems enable life to continue
not when Life-supporting can describe a habitat broadly and may not indicate medical necessity.
literary
sustaining
continued strength or existence is being supported
not when Sustaining alone can refer to morale, attention, or institutions.

life-sustaining treatment
The patient discussed life-sustaining treatment with her family and physician.
life-sustaining supplies
Boats delivered life-sustaining supplies after the road washed out.
life-sustaining water
The restored spring provides life-sustaining water through the dry season.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.