requisite

adj. required, essential, necessary, needed

n. necessity, something that is required

Noun
1. 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"
(synonym) necessity, essential, requirement, necessary
(hypernym) thing
(hyponym) desideratum
Adjective
1. necessary for relief or supply; "provided them with all things needful"
(synonym) needed, needful, required
(similar) necessary

v. requisition, require; commandeer

v. solicit; embargo; requisition

(n.)
That which is required, or is necessary; something indispensable.
  

(a.)
Required by the nature of things, or by circumstances; so needful that it can not be dispensed with; necessary; indispensable.