The phrase "cold blooded" is commonly used to describe someone who is unemotional or ruthless. The spelling of this phrase can be broken down using IPA phonetic transcription as /kəʊld/ /blʌdɪd/. The first syllable, "kold," has a long "o" sound and is pronounced with the tongue slightly lowered and pulled towards the back of the mouth. The second syllable, "bludid," has a short "u" sound and is pronounced with the tongue pressed against the roof of the mouth.
Cold-blooded is an adjective that describes an animal's ability to regulate its body temperature independently of the environment. Specifically, it refers to creatures whose body temperature fluctuates according to their surrounding environment. These animals, known as ectotherms, lack the ability to internally produce and maintain a stable body temperature. Instead, they rely on external sources of heat, such as the sun or warm surfaces, to raise their body temperature or shade and cool places to lower it.
Cold-blooded animals include reptiles (such as snakes, lizards, and turtles), amphibians (like frogs, toads, and salamanders), and a variety of invertebrates (such as insects and crustaceans). Their internal temperature is similar to that of their surrounding environment, enabling them to adapt to a wide range of habitats and climates. Unlike warm-blooded animals (endotherms), which can generate their own body heat by metabolic processes, cold-blooded creatures must strategically regulate their temperature by moving to warmer or cooler areas as needed.
The term "cold-blooded" is often used metaphorically to describe a person who lacks emotions, showing a deliberate and calculated approach to situations without being influenced by strong feelings. In this context, it characterizes someone who displays a detached, unemotional, or unresponsive demeanor in certain circumstances.
The phrase "cold-blooded" originated from the ancient belief that different animals have unique types of blood. In the medieval era, it was commonly believed that mammals and birds possessed warm blood, while reptiles, amphibians, and insects had cold blood.
The term "cold blooded" first appeared in the English language in the 16th century, directly referring to the concept of reptilian physiology. Over time, it evolved to describe a characteristic or behavior lacking warmth, sympathy, or emotion. In a figurative sense, being "cold-blooded" came to imply being unfeeling, callous, or lacking in compassion.