If you refer to a decision, event, or change as momentous, you mean that it is very important, often because of the effects that it will have in the future. 重大的
adjective [原级] 重大的，重要的
These same cycles of change had momentous impacts on the sparse human populations of the region. 这些相同的变化周期对该区域稀少的人口产生了重大影响。
