Acrolein

noun

1. A colorless, flammable, poisonous liquid aldehyde, C3H4O, having an acrid odor and vapors irritating to the eyes.
2. A colorless limpid liquid, CH2CHCOH, having a disagreeable and intensely irritating odor, such as that noticeable after the flame of a candle has been extinguished and while the wick still glows.
3. A limpid, colorless, highly volatile liquid, obtained by the dehydration of glycerin, or the destructive distillation of neutral fats containing glycerin. Its vapors are intensely irritating.
4. A pungent, acrid, poisonous liquid aldehyde, CH2=CH-CH=O, made by the destructive distillation of glycerol.
5. a pungent colorless unsaturated liquid aldehyde made from propene