Synonyms: indispensable
Definition: unavoidable
Usage: the routine but indispensable ceremonies of state
Similar words: obligatory
Definition: morally or legally constraining or binding
Usage: attendance is obligatory; an obligatory contribution
Synonyms: indispensable
Definition: not to be dispensed with; essential
Usage: foods indispensable to good nutrition
Similar words: critical, vital
Definition: urgently needed; absolutely necessary
Usage: a critical element of the plan; critical medical supplies; vital for a healthy society; of vital interest
Synonyms: indispensable, essential
Definition: absolutely necessary; vitally necessary
Usage: essential tools and materials; funds essential to the completion of the project; an indispensable worker
Similar words: necessary
Definition: absolutely essential