"냉혈" (naenghyeol) translates to "cold-blooded" in English and refers to animals that rely on external environmental temperatures to regulate their body heat. This term is commonly associated with species such as reptiles, amphibians, and fish, which do not generate their own body heat. Instead, they absorb warmth from their surroundings, making them dependent on the climate for their metabolic processes. In a broader context, "냉혈" can also describe behaviors or characteristics in humans, often implying a lack of empathy or emotional warmth. This metaphorical use suggests a person who is detached or unfeeling, similar to how cold-blooded animals may appear indifferent to their environment.