adj.1. Relating to or resembling vapor: "They saw wild horses racing on the plain ... leaving in the moonlight a vaporous dust" (Cormac McCarthy).
2. a. Producing vapors; volatile.
b. Full of vapors.
3. Insubstantial, vague, or ethereal: "the imponderable mysterious and vaporous illusions of twilight" (John C. Powys).
4. Extravagantly fanciful; high-flown: vaporous conjecture.