Freezes is a word used to describe a state of immobility or stiffness. There are several synonyms that can be used to describe the same condition. One of such words is "stiffens," which implies that something becomes rigid or hard to move. Another useful synonym is "solidifies," which means that a liquid or soft substance becomes hard or firm, or turns to ice. Yet another synonym for freezes is "coagulates," which is used to describe a process where a fluid, like blood, forms a clot or thickens. So, depending on the context, there are many suitable words that can be used instead of freezes.