all-important, critical, essential, imperative, indispensable, integral, must-have, necessary, necessitous, needed, needful, required, requisite, vital

prerequisitecompulsory, mandatory, nonelective, obligatoryconsequential, crucial, important, major, material, meaningful, momentous, significant, substantial, weightybasic, central, fundamental, key, organicinsistent, persistent, pressing, urgent

dispensable, inessential, needless, nonessential, unessential, unnecessary, unneeded

undesired, unwantedinconsequential, insignificant, unimportantexcess, external, extra, extraneous, superfluous, surplus