/ vɑːst; NAmE væst/ adjective
extremely large in area, size, amount, etc.
SYN huge :
a vast area of forest
a vast crowd
a vast amount of information
At dusk bats appear in vast numbers .
His business empire was vast.
In the vast majority of cases, this should not be a problem.
► vast·ness noun [ U , C ]:
the vastness of space
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WORD ORIGIN
late Middle English : from Latin vastus void, immense.