The crossword solution for the term 'convert from fluid to solid state' is 'COAGULATE, ' which is a nine-letter word. Coagulation is a process in which a liquid changes into a solid or semi-solid state. It is often used in the context of blood clotting, but it can also refer to the process of turning a liquid into a gel or jelly-like substance. Coagulation is a physical process that occurs when particles in a liquid come together and form a larger mass. This process is often used in the food industry to turn liquids into solids, such as when milk is turned into cheese.