Meaning: Absolutely necessary.
Example: he made himself indispensable to the parish priest
Synonyms: essential, crucial, necessary, key, vital, needed, required, called for, requisite, important, all-important, vitally important, of the utmost importance, of great consequence, of the essence, critical, life-and-death, imperative, mandatory, compulsory, obligatory, compelling, urgent, pressing, burning, acute, paramount, pre-eminent, high-priority, significant, consequential