Vastly means to an extremely great degree or extent.
例句
The jury has heard two vastly different accounts of what happened.陪審團聽到了對所發生事件的兩種截然不同的陳述。...cars that are vastly more competitive.更富競爭力、優勢極為明顯的汽車
英漢詞典釋義
adv.
極大地
a microwave that is vastly superior in design to all other models設計上大大優于其他型號的微波爐Death was considered vastly preferable to dishonour.可殺不可辱。Her private and public selves were vastly different.她人后的本相與人前的形象大為不同。
英英詞典釋義
Adverb
1. to an exceedingly great extent or degree;
"He had vastly overestimated his resources""was immensely more important to the project as a scientist than as an administrator"