An unpleasant thing to be. Abandoned, desolate. Chill.
One is often left cold and alone. It is an active term, although it describes a state of stasis. One is actively abandoned, or actively pushes people away and then feels abandoned anyway. One is left, resulting in the state of "alone". You are left out in the cold. No one is thinking about you, no one loves you. If they cared, they would not have left. But they left.
When one is only taken care of in a perfunctory sort of way, as opposed to out of any good will or god knows affection. For example, life in the orphanage. Here is your sandwich wash your face time to go to school you'll be late. You're five minutes late don't let it happen again do your homework eat your dinner I expect these dishes clean brush your teeth aren't you in bed yet? You are in bed, in your dark sterile room, hollow, clean and healthy and cold. You have no one to talk to. No one talks to you. You are organized and then ignored, or worse, forgotten.
Read me a story? You're too big for a story now go to sleep.
Out in ancient Sparta, on the hill. Tiny girl babies or premature twins or the ill or deformed babies. These are the best example of cold and alone. They cannot understand why. They do not yet have the mental capacity to take it in at all. They only know they are alone in the dark and the cold. They wail. And then there are wolves.