All 3 Uses

subsist
in
The History of Love
(Auto-generated)

Sometimes she subsists for days on water and air.†
*

subsists = survives
They realized that these strange organisms were subsisting on the hydrogen sulfide spewed from the vents, and breathing out sulfur the way plants on land produce oxygen.†

subsisting = surviving
ONE THING I AM NEVER GOING TO DO WHEN I GROW UP Is fall in love, drop out of college, learn to subsist on water and air, have a species named after me, and ruin my life.†

subsist = survive

Definitions:

(1) (subsist)
to survive or exist -- especially without being able to manage comforts or luxuries
(2) (meaning too rare to warrant focus)