1. essential, necessary, necessity, requirement, requisite

anything indispensable

Example Sentences:
'food and shelter are necessities of life'
'the essentials of the good life'
'allow farmers to buy their requirements under favorable conditions'
'a place where the requisites of water fuel and fodder can be obtained'

• necessary
• necessity
• requirement
• requisite

2. essential, indispensable

absolutely necessary; vitally necessary

Example Sentences:
'essential tools and materials'
'funds essential to the completion of the project'
'an indispensable worker'

• indispensable

3. essential

basic and fundamental

Example Sentences:
'the essential feature'

• basal
• primary
• biogenic
• constituent
• constitutional
• constitutive
• organic
• life-sustaining
• vital
• must
• no-frills
• staple
• substantial
• substantive
• virtual

• crucial
• important
• important
• of import
• indispensable
• intrinsic
• intrinsical
• necessary
• primary
• unexpendable

4. all important, all-important, crucial, essential, of the essence

of the greatest importance

Example Sentences:
'the all-important subject of disarmament'
'crucial information'
'in chess cool nerves are of the essence'

• all important
• all-important
• crucial
• of the essence

• important
• of import

5. essential

being or relating to or containing the essence of a plant etc

Example Sentences:
'essential oil'

6. essential, substantive

defining rights and duties as opposed to giving the rules by which rights and duties are established

Example Sentences:
'substantive law'

• substantive