| required(adjective, right, important, capital, essential) |
| essential(noun, adjective, body, material, big) |
| requisite(noun, adjective, important, want, need) |
| indispensable(adjective, important, significant, original, essential) |
| vital(adjective, body, material, big, important) |
| obligatory(adjective, sound, right, essential, obligation) |
| fundamental(noun, adjective, body, material, important) |
| imperative(adjective, important, essential, critical, vital) |
| compulsory(adjective, cruel, essential, pitiless, obligation) |
| important(adjective, significant, original, substantial, serious) |
| prerequisite(noun, adjective, important, want, need) |
| unavoidable(adjective, regular, essential, obvious, bound) |
| urgent(adjective, important, substantial, valuable, essential) |
| crucial(adjective, big, important, significant, original) |
| needful(adjective, set, important, original, capital) |
| organic(adjective, important, significant, natural, animate) |
| necessity(noun, want, need, essential, basic) |
| mandatory(adjective, right, essential, obvious, obligation) |
| inevitable(adjective, certain, regular, obvious, expected) |
| needed(adjective, essential, important, critical, verb) |