Populace, in its original use, was a negative way of referring to ordinary people, as opposed to rich, privileged, or royal people. A king might try to understand the mindset of the populace, but it's likely that he had no idea what their lives were really like. Populace can also be a neutral term that refers to a group of people living in a particular place. For example, New York City has a populace of about eight million people.