[adjective] -er, -est - extremely bigIn 1918 the Bolsheviks used radio to help spread revolution across a vast country.A vast audience watched the broadcast.The amount of detail the book contains is vast.The people who have taken our advice have saved themselves a vast amount of money.The vast majority of pupils attend state schools.
VAST
Meaning of VAST in English
Cambridge English vocab. Кембриджский английский словарь. 2012