NECESSARY

1. [n] anything indispensable; "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"

2. [s] unavoidably determined by prior circumstances; "the necessary consequences of one''s actions"

3. [a] absolutely essential

similar words

1. [a] inevitable

2. [s] essential

3. [s] indispensable

4. [s] needed

5. [s] needful

6. [s] required

7. [s] requisite

8. [s] obligatory

opposite words

1. [n] inessential

2. [n] nonessential

3. [a] unnecessary

4. [a] unneeded