absolutely required and not to be used up or sacrificed
absolutely necessary; vitally necessary; "essential tools and materials"; "funds essential to the completion of the project"; "an indispensable worker"
being or relating to or containing the essence of a plant etc; "essential oil"
anything indispensable; "food and shelter are necessities of life"; "the essentials of the good life"; "allow farmers to buy their requirements under favorable conditions"; "a place where the requisites of water fuel and fodder can be obtained"
an official form on which a request in made; "first you have to fill out the requisition"
the act of requiring; an authoritative request or demand, especially by a military or public authority that takes something over (usually temporarily) for military or public use
make a formal request for official services
demand and take for use or service, especially by military or public authority for public service