| necessary(adjective, important, essential, critical, vital) |
| essential(noun, adjective, form, fix, pass) |
| urgent(adjective, strong, firm, prompt, big) |
| important(adjective, significant, substantial, serious, valuable) |
| indispensable(adjective, important, significant, serious, essential) |
| requisite(noun, adjective, important, need, significant) |
| pressing(adjective, firm, prompt, big, important) |
| obligatory(adjective, important, significant, essential, basic) |
| crucial(adjective, big, important, determined, significant) |
| required(adjective, important, significant, essential, critical) |
| critical(adjective, big, important, determined, significant) |
| peremptory(adjective, government, duty, severity, oppressive) |
| vital(adjective, big, important, significant, substantial) |
| exigent(adjective, firm, prompt, big, important) |
| compulsory(adjective, set, important, significant, essential) |
| prerequisite(noun, adjective, form, fix, pass) |
| mandatory(adjective, set, significant, essential, basic) |
| must(noun, adjective, need, essential, obligation) |
| commanding(adjective, authoritative, domineering) |
| needful(adjective, set, important, significant, capital) |