| big(important, significant, historic) |
| chips are down(expression, idiom, important, significant, historic) |
| considerable(important, significant, historic) |
| decisive(important, significant, historic) |
| earth-shaking(important, significant, historic) |
| earth-shattering(important, significant, historic) |
| epochal(important, significant, historic) |
| eventful(important, significant, historic) |
| far-reaching(important, significant, historic) |
| fateful(important, significant, historic) |
| grave(important, significant, historic) |
| heavy(important, significant, historic) |
| historic(important, significant) |
| important serious(expression, important, significant, historic) |
| material(important, significant, historic) |
| memorable(important, significant, historic) |
| momentous(adjective, important, significant, historic) |
| of moment(expression, important, significant, historic) |
| outstanding(important, significant, historic) |
| substantial(important, significant, historic) |