critical
necessary
obligatory
vital
bare necessities
basic
bedrock
call for
called for
cardinal
central
compelling
compulsory
crucial
demand
demand for
demanded
desideration
desideratum
essential
essentials
focal
fundamental
imperative
important
in demand
indicated
ineluctable
inescapable
inevitable
irreducible
irreductible
irreplaceable
key
life-and-death
life-or-death
mandatory
material
must
must item
necessaries
necessities
necessitous
necessity
need
need for
needed
needful
occasion
of the essence
of vital importance
beneficial
desirable
invaluable
requisite
compensable
comprehensible
defensible
dispensable
indefensible
insensible
ostensible
reprehensible
sensible