va·por / ˈvāpər/ (Brit. va·pour) • n. a substance diffused or suspended in the air, esp. one normally liquid or solid: dense clouds of smoke and toxic vapor| chemical vapors. ∎  Physics a gaseous substance that is below its critical temperature, and can therefore be liquefied by pressure alone. Compare with gas. ∎  (the vapors) dated a sudden feeling of faintness or nervousness or a state of depression.• v. [intr.] talk in a vacuous, boasting, or pompous way: he was vaporing on about the days of his youth.DERIVATIVES: va·por·ish adj. ( archaic )va·por·ous / ˈvāpərəs/ adj.va·por·ous·ness / ˈvāpərəsnəs/ n.va·por·y / ˈvāpərē/ adj.

vapour steam, steamy exhalation XIV; (pl.) exhalations arising in the human body XV; (arch.) morbid condition resulting from these XVII. — (O)F. vapeur, †-our or L. vapor, -ōr- steam, heat; see -OUR2.
So vaporous XVI. f. late L. vapōrus or — late L. vapōrōsus.