requisite

(noun) anything indispensable. Synonyms: necessity, essential, requirement, necessary. Examples: "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."

(adj) necessary for relief or supply. Synonyms: needed, needful, required. Example: "Provided them with all things needful."