marked by deprivation especially of the necessities of life or healthful environmental influences; "a childhood that was unhappy and deprived, the family living off charity"; "boys from a deprived environment, wherein the family life revealed a pattern of neglect, moral degradation, and disregard for law"
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"