vast

adjective3

1. •
   extremely large, or covering a very wide area

   • The Sahara desert is vast.
   • There is a vast difference between them.
2. •
   Very great in size, amount, degree, intensity, or especially extent.

   • The exiguity and smallnesse of some seeds extending to large productions is one of the magnalities of nature, somewhat illustrating the work of the Creation, and vast production from nothing. — 1658
3. •
   (no longer used) Waste; desert; desolate; lonely.

noun1

1. •
   (literary) A vast space.

   • they have seemed to be together, though absent, shook hands, as over a vast, and embraced, as it were, from the ends of opposed winds. — 1610

noun2

1. •
   Acronym of visual audio sensory theater.
2. •
   Acronym of volcanic ash strategic initiative team.