Vast, a. [Compar. Vaster; superl. Vastest.]
Etymology: [L. vastus empty, waste, enormous, immense: cf. F. vaste. See Waste, and cf. Devastate.]
1. Waste; desert; desolate; lonely. [Obs.] The empty, vast, and wandering air. Shak.
2. Of great extent; very spacious or large; also, huge in bulk; immense; enormous; as, the vast ocean; vast mountains; the vast empire of Russia. Through the vast and boundless deep. Milton.
3. Very great in numbers, quantity, or amount; as, a vast army; a vast sum of money.
4. Very great in importance; as, a subject of vast concern.
1 more senses
Syn. -- Enormous; huge; immense; mighty.
1 other Webster entry under this spelling
Vast, n.
A waste region; boundless space; immensity. "The watery vast." Pope. Michael bid sound The archangel trumpet. Through the vast of heaven It sounded. Milton.
Shades of meaning
Fernald has no entry of its own for vast; he lists it under large.
He lists it without comment; the entries above explain its neighbors.