Become lumpy is a term used to describe a process that can occur when certain liquids are exposed to certain conditions. CURDLE, a 6-letter word, is the process of a liquid becoming thick and semi-solid due to the action of bacteria, enzymes, or acids. CLOT, a 4-letter word, is the process of a liquid becoming thick and solid due to the action of heat or an agent such as a chemical. Both processes result in a liquid becoming lumpy.