A round character is one who is fully developed and described in detail. These are characters we know a lot about. We know what they look like, and how they act, and what their motivations are. These are the main characters. In The Giver, the most significant round characters are Jonas and The Giver. These are the only two characters we really understand and know a lot about.
A flat character is not well-developed. We may know a few details about this character, such as what he or she looks like, but we don’t really know what the person is thinking or feeling or understand his or her actions. These are the supporting characters, who are named but not much else. Fiona is an example.
A static character does not change throughout the story. Unlike the main character, who grows and changes, static characters stay the same no matter what. An example is Jonas’s mother and father. We know very little about them, but we do know that they never change. For instance, we know that Jonas’s father seems to care about newchildren, but he also willingly kills a newborn. Asher is also a static character.
A dynamic character changes throughout the course of the story. In The Giver, the only people who change in any meaningful way are Jonas and The Giver. Jonas is the biggest example, because he matures and changes tremendously throughout the story. He also sparks change in The Giver though, as The Giver does decide to help Jonas change the community.