Definition of vast

• superl. - Waste; desert; desolate; lonely.
• 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.
• superl. - Very great in numbers, quantity, or amount; as, a vast army; a vast sum of money.
• superl. - Very great in importance; as, a subject of vast concern.
• n. - A waste region; boundless space; immensity.