optional Antonyms

obligatory same thing desperately needed absolutely necessary badly needed absolutely essential sorely needed much needed nonoptional non-optional bigass big ass nonvoluntary nonelective obbligato highly necessary highly needed highly required very necessary very much needed very essential urgently required urgently needed so needed so badly required so badly needed death and taxes very important required badly really needed really necessary quite necessary mandatorily off-the-cuff unavoidable ineludible indispensable incumbent important imperative forced essential enforced dictated compulsory bounden basic avoidless automatic inevitable