| basic(adjective, significant, essential, vital, fundamental) |
| bottom line(expression, fundamental, decisive, imperative) |
| cardinal(adjective, significant, essential, basic, vital) |
| dangerous |
| earth-shaking(adjective, important, serious, critical, earthshaking) |
| earth-shattering(adjective, important, serious, critical, earthshaking) |
| earthshaking(adjective, important, serious, critical) |
| earthshattering(adjective, important, serious, critical, earthshaking) |
| elementary(adjective, significant, essential, basic, vital) |
| exceptive(adjective, significant, serious, vital, grave) |
| extremely important(expression, adjective, important, serious, critical) |
| famous(adjective, special) |
| grave |
| high-priority(adjective, significant, serious, vital, grave) |
| high priority(expression, adjective, significant, serious, vital) |
| key(adjective, special) |
| life-threatening |
| life and death(expression, adjective, idiom, earthshaking) |
| life or death(expression, adjective, idiom, important, serious) |
| much-repeated(adjective, special) |