English▸ noun
1 a substance diffused or suspended in the air, especially 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.
2 (the vapors) dated a sudden feeling of faintness or nervousness or a state of depression:
a fit of the vapors.
▸ verb [no object] talk in a vacuous, boasting, or pompous way:
he was vaporing on about the days of his youth.
– ORIGIN late Middle English : from Old French, or from Latin vapor ‘steam, heat’. The current verb sense dates from the early 17th century.