| required(adjective, important, significant, serious, essential) |
| essential(adjective, characteristic, important, significant, original) |
| necessary(adjective, important, significant, original, essential) |
| imperative(adjective, important, significant, serious, essential) |
| requisite(adjective, important, significant, original, essential) |
| vital(adjective, important, significant, original, serious) |
| crucial(adjective, important, significant, original, serious) |
| important(adjective, significant, serious, essential, critical) |
| obligatory(adjective, important, significant, essential, critical) |
| mandatory(adjective, set, significant, essential, basic) |
| needed(adjective, set, important, significant, essential) |
| fundamental(adjective, characteristic, important, significant, natural) |
| needful(adjective, set, important, significant, capital) |
| compulsory(adjective, set, important, significant, essential) |
| prerequisite(adjective, important, significant, essential, critical) |
| basic(adjective, characteristic, important, significant, natural) |
| urgent(adjective, important, significant, serious, essential) |
| demanded |
| key(adjective, important, significant, essential, critical) |
| inevitable(adjective, required, obligatory) |