For centuries, the body's blood has been linked closely with the emotions.People who show no human emotions or feelings, are said to be cold-blooded killer.For example, the police are searching for a cold-blooded killer.He seems to kill for no reason, and no emotion, as if taking someone's life as nothing. Cold can affect other parts of the body.The expression "get cold feet" has nothing to do with cold or your feet.The expression means being afraid to do something you have decided to do.For example, you agree to be president of an organization.But then you learn that all the other officers have resigned, and all the work of the organizations will be your responsibility.You are likely to get cold feet about being president when you understand the situation. The expression "give someone the cold shoulder" probably comes from the physical act of turning your back toward someone, instead of speaking to him face to face.You may give a cold shoulder to a friend who has not kept a promise he made to you.Or, to someone who has lied about you to others. A cold fish is not a fish.It is a person.But it is a person who is unfriendly, unemotional and shows no love or warmth.A cold fish does not offer much of himself to anyone.Someone who is a cold fish could be cold-hearted.Now a cold-hearted person is someone who has no sympathy.Several popular songs in recent years were about cold-hearted men or cold-hearted women who, without feelings, broke the hearts of their lovers. "Out in the cold" means not getting something that everybody else got.A person might say that everybody but him got a pay raise----he was left out in the cold.And it is not a pleasant place to be. We can use the expression "  _  " to describe a man who abandons or hurts his lover without mercy.
cold-blooded cold shoulder cold feet cold-hearted