cold-blooded.

This term is used in a popular fashion, for some creatures when talking about temperament – horses are sometimes referred to as being hot-blooded(such as thoroughbreds) warm-blooded(Thoroughbred-crosses and some other types) cold-blooded(such as drafts- not because they are mean, but because they are so complacent).

And, then there are the “cold-blooded killer(s), who seem possess no remorse. Probably the best and more accurate term for the last would be “socio-path”.

Since that time, advances in the study of how creatures maintain their internal temperatures (termed: Thermophysiology) have shown that many of the earlier notions of what the terms “warm-blooded” and “cold-blooded” mean, were far from accurate (see below: breaking down cold-bloodedness). Today scientists realize that body temperature types are not a simple matter of black and white. Most creatures fit more in line with a graded spectrum from one extreme (cold-blooded) to another (warm-blooded).