| unavoidable(adjective, set, significant, essential, basic) |
| cardinal(adjective, important, significant, original, essential) |
| central(adjective, important, significant, serious, basic) |
| compelling(adjective, important, significant, serious, essential) |
| critical(adjective, important, original, serious, essential) |
| inescapable(adjective, required) |
| must(adjective, required) |
| necessitous(adjective, important, capital, essential, vital) |
| of the essence(expression, adjective, idiom, important, essential) |
| pressing(adjective, important, significant, essential, critical) |
| primary(adjective, important, significant, original, serious) |
| staple |
| in demand(expression, adjective, idiom, requirement) |
| integral(adjective, important, original, essential, critical) |
| life-and-death(adjective, important) |
| material(noun, adjective, important, relevant) |
| substantive |
| binding(adjective, significant, essential, basic, vital) |
| called for(verb, expression, phrasal verb, essential, requirement) |
| demand |