The term FORM A SOLIDIFIED MASS can be summarized by the crossword solution CLOT, which is a four-letter word. A CLOT is a mass of coagulated blood or other bodily fluid that has solidified. Clots are formed when proteins in the blood interact with each other and form a gel-like substance. Clots can be beneficial, such as when they form to stop bleeding, but they can also be dangerous if they form in the wrong place, such as in the lungs or brain.