Definition: The word "curdling" refers to the process where a liquid, especially milk, thickens and forms small, semisolid lumps. This usually happens when an acid (like lemon juice or vinegar) is added to milk or when milk is heated.
In a more advanced context, "curdling" can be applied metaphorically. For example, one might say that a situation is "curdling" when it is becoming tense or uncomfortable, much like how milk curdles when it is disturbed.