The term VAST QUANTITY can be described by four different crossword solutions: TONS (4 letters), OCEAN (5 letters), SLEW (4 letters), and MULTITUDE (9 letters). TONS is a unit of measurement for a large amount of something, usually referring to weight. OCEAN is a large body of salt water that covers most of the Earth's surface. SLEW is an informal term for a large number or amount of something. MULTITUDE is a large group of people or things. SEA is a large body of salt water that is smaller than an OCEAN. All of these words describe a large quantity of something, which is what VAST QUANTITY means.