Available Definitions:
1) superl. - Waste; desert; desolate; lonely.
2) superl. - Of great extent; very spacious or large; also, huge in bulk; immense; enormous; as, the vast ocean; vast mountains; the vast empire of Russia.
3) superl. - Very great in numbers, quantity, or amount; as, a vast army; a vast sum of money.
4) superl. - Very great in importance; as, a subject of vast concern.
5) n. - A waste region; boundless space; immensity.