Emily Dickinson Lexicon

VAST, a. [L. vastus; Fr. vaste; It. vasto. The primary sense of the root must be to part or spread, as this is connected with the verb to waste.]

1. Being of great extent; very spacious or large; as, the vast ocean; a vast abyss; the vast empire of Russia; the vast plains of Syria; the vast domains of the Almighty.
2. Huge in bulk and extent; as, the vast mountains of Asia; the vast range of the Andes.
3. Very great in numbers or amount; as, a vast army; vast numbers or multitudes were slain; vast sums of money have been expended to gratify pride and ambition.
4. Very great in force; mighty; as, vast efforts; vast labor.
5. Very great in importance; as, a subject of vast concern.