Emily Dickinson Lexicon

VA'POR, n. [L. and Sp. vapor; Fr. vapeur; It. vapore. It is probably from a verb signifying to depart, to fly off.]

1. In a general sense, an invisible elastic fluid, rendered aeriform by heat, and capable of being condensed, or brought back to the liquid or solid state, by cold. The vapor of water is distinguished by the name of steam, – which see.
2. A visible fluid floating in the atmosphere. All substances which impair the transparency of the atmosphere, as smoke, fog, &c., are in common language called vapors, though the term vapor is technically applied only to an invisible and condensible substance, as in No. 1; fog, &c. being vapor condensed, or water in a minute state of division. Vapor rising into the higher regions of the atmosphere, and condensed in large volumes, forms clouds. – D. Olmsted.
3. Substances resembling smoke, which sometimes fill the atmosphere, particularly in America during the autumn.
4. Wind; flatulence. – Bacon.
5. Mental fume; vain imagination; unreal fancy. – Hammond.
6. Vapors, a disease of nervous debility, in which a variety of strange images float in the brain, or appear as if visible. Hence hypochondriacal affections and spleen are called vapors.
7. Something unsubstantial, fleeting, or transitory. For what is your life? It is even a vapor, that appeareth for a little time, and then vanisheth away. James iv.