The phrase "as cold as ice" has two basic meanings. In some cases, it means a person or object is very cold. For example, a person's hands may be described being ice cold when he returns inside from spending time outdoors on a cold winter day. It is also used to describe the state of a person's emotions. For instance, a person may be described as cold as ice when others believe he lacks feelings. The phrase is not meant literally in either case.
Since water must freeze in order to become ice, people often use ice as a comparison for things they consider very cold. An individual can also use this phrase to describe the feeling of the temperature in a room or the feel of the tip of a person's nose. Additionally, an individual could use this phrase to describe himself. For instance, if he is feeling very chilled, he might say he is as cold as ice, or he could use this phrase to describe the temperature of his ungloved hands.
Sometimes the phrase is used to describe a person's emotions, or rather, the lack of them. For example, this phrase is often used to describe a person in an unfavorable manner. It essentially means that the person is lacking in emotion. There are many types of situations in which this phrase can be used appropriately. A good example, however, is a situation in which a person lacks sympathy for another or does not seem to care about another party's emotional or physical pain.
It is important to note that, in most cases, people do not use this phrase literally. Instead, they use it to compare something to freezing temperatures despite the fact that the item or person isn't actually freezing. The phrase is a commonly used idiom, which is a word or phrase that is used in everyday speech and has a commonly known meaning but is not meant to be taken literally.
Interestingly, the phrase is often used in song lyrics. A person can hear it in many different love songs, especially those about a person who has been jilted or otherwise wronged by his lover. For instance, song lyrics might describe a person whose lover has been unfaithful to him and then treated him as cold as ice afterwards.