Acetaldehyde is an organic compound with the chemical formula CH3CHO. It is also known as ETHANAL, which is the seven-letter solution to the crossword puzzle. Acetaldehyde is a colorless, flammable liquid with a pungent odor. It is produced naturally in small amounts by plants and animals, and is used in the production of many industrial chemicals. Acetaldehyde is also used as a flavoring agent in food and beverages.