That cannot be avoided; inevitable
Necessary to continued existence or effectiveness:
Required by fashion; fashionable
The definition of obligatory is necessary, required or expected as a result of law or social custom.
Pertaining to the foundation or basis; serving for the foundation. Hence: Essential, as an element, principle, or law; important; original; elementary.
Being a substance that is required for normal functioning but does not need to be included in the diet because of the body's ability to synthesize it from other nutrients:
The definition of requisite is something required or necessary.
The definition of important is having great significance or consequence.
(Biochemistry) Being a substance that is required for normal functioning but cannot be synthesized by the body and therefore must be included in the diet:
Incapable of being dispensed with
Of, being, or serving as a starting point or basis:
Of main importance; principal; chief
Vital to the resolution of a crisis or the determination of an outcome:
The definition of imperative is something that has authority or is absolutely necessary.
Necessary for completeness; essential
The definition of needful is something that is required.
Required beforehand, esp. as a necessary condition for something following
Essential quality, fact, or thing
Being more than is needed, useful, or wanted; surplus; excessive
The definition of redundant is more than enough or too much of something.
Find another word for indispensable. In this page you can discover 32 synonyms, antonyms, idiomatic expressions, and related words for indispensable, like: unavoidable, necessary, needed, vital, de rigueur, obligatory, fundamental, nonessential, requisite, important and indispensible.