1. very large areas or stretches of land, water, or space
The vast expanses of the Amazon rainforest are home to countless species.
As extensões vastas da floresta amazônica abrigam inúmeras espécies.
2. wide, open regions without apparent limits or boundaries
Travelers crossed the vast expanses of the desert for weeks.
Os viajantes atravessaram as extensões vastas do deserto por semanas.