The term 'LAB COMPOUND' can be broken down into two crossword solutions: ENOL (4 letters) and ESTER (5 letters). ENOL stands for a type of organic compound that contains a hydroxyl group (-OH) and a double bond between two carbon atoms. It is also known as an alpha-hydroxy ketone or aldehyde. ESTER, on the other hand, is an organic compound that is formed when an acid reacts with an alcohol. It is characterized by the presence of an oxygen atom that is connected to two alkyl groups. Both ENOL and ESTER are important compounds in organic chemistry and are used in various laboratory experiments.