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"
- His father was vastly pleased with him.
- His piano playing has vastly improved since last year.
- The power and influence of even the present-day Internet is vastly underestimated.
- A little change on this painting made it vastly different.