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 mandatorily highly necessary highly needed 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 highly required off-the-cuff unavoidable indispensable incumbent important imperative forced fascicle essential enforced dictated compulsory bounden basic avoidless automatic ineludible