Source : Webster's Revised Unabridged Dictionary (1913)

Vaporous \Va"por*ous\, a. [L. vaporosus: cf. vaporeux.]
   1. Having the form or nature of vapor. --Holland.

   2. Full of vapors or exhalations. --Shak.

            The warmer and more vaporous air of the valleys.
                                                  --Derham.

   3. Producing vapors; hence, windy; flatulent. --Bacon.

            The food which is most vaporous and perspirable is
            the most easily digested.             --Arbuthnot.

   4. Unreal; unsubstantial; vain; whimsical.

            Such vaporous speculations were inevitable.
                                                  --Carlyle.

Source : WordNet®

vaporous
     adj 1: so thin as to transmit light; "a hat with a diaphanous
            veil"; "filmy wings of a moth"; "gauzy clouds of
            dandelion down"; "gossamer cobwebs"; "sheer silk
            stockings"; "transparent chiffon"; "vaporous silks"
            [syn: {diaphanous}, {filmy}, {gauzy}, {gossamer}, {see-through},
             {sheer}, {transparent}, {cobwebby}]
     2: resembling or characteristic of vapor; "vaporous clouds"
        [syn: {vaporific}, {vaporish}, {vapourish}]
     3: filled with vapor; "miasmic jungles"; "a vaporous bog" [syn:
         {miasmal}, {miasmic}]