In a recent read of Bill Bryson's In A Sunburned Country was this sentence: "He killed several people, often in cold blood, sometimes for no very good reason." That sentence made me stop and wonder where that came from. Warm blooded mammals killed in cold blood. Hmmm.
The question -- what is the derivation of the phrase "killed...in cold blood".
Lloyd
I didn't really understand this phrase either, until I learned about the French phase "garder son sang-froid," or "keeping one's blood cold" which is used as we would say to keep your cool, to not lose your temper, to start to panic. Doing something in cold blood means that you're not in the middle of a heated, emotional confrontation; you're completely cool and relaxed and in full control. It just seems that the "blood" part of these other expressions (to keep your cool, a heated exchange) sort of dropped off in English.
It didn't occur to me that the person doing the killing had the cold blood! When I hear that phrase in the future I will interpret, "He, in cold blood, killed several people for no reason at all."
Yup, aj318 has it right. The idea is indeed sang-froid.
Also, it can refer to merciless manslaughter: having no feeling for the person you are killing; doing it as simply and phlegmatically as opening a bottle of GlycoLax. The English language can be downright gruesome at times!