Necessary

Adjective absolutely essential, unavoidably determined by prior circumstances, Impossible to be otherwise, or to be dispensed with, without preventing the attainment of a desired result; indispensable; requisite; essential, noun_ A thing that is necessary or indispensable to some purpose; something that one can not do without; a requisite; an essential; -- used chiefly in the plural, Anything that is necessary or indispensable; that which cannot be disregarded or omitted_ as, the necessaries of life, Something indispensable