
Indispensable
Non-substitutable
Use 'indispensable' when something can't be replaced because it's too important.

A smartphone has become an indispensable device for modern communication.
Vital Importance
'Indispensable' suggests that without the item or person, a task would fail or a goal couldn't be achieved.

Her expertise in coding is indispensable to the success of the project.
Often Overlooked
Sometimes, 'indispensable' items or skills are taken for granted, but are crucial in certain situations.

In case of emergency, a flashlight is indispensable.
Compare with
CriticalEssentialImperativeImportantIntegralNecessaryObligatoryRequisiteVital
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