A static character is a minor character that does not undergo any character development. Examples of static characters in Pride and Prejudice are: all three of the younger sisters, Mrs. Bennet, Charlotte, Mr. Collins, Lady Catherine de Bourgh, Ann de Bourgh, and Bingley's sisters.
However, a static character can either be round or flat. A flat character is character who is not very rich in personality. A round character, like a real person, has a much more complicated personality. Very few of Austen's characters are flat. The only real static flat characters are Lydia, and Ann de Bourgh. Lydia is flat because all she is is a silly, flirtatious girl who does not have her head on straight. Ann de Bourgh is flat because we never actually learn anything about her accept that her health is poor and that she is allegedly betrothed to Darcy. We never actually hear her speak.
A dynamic character is a major character that undergoes changes. Examples of those are Elizabeth, Jane, Darcy, Bingley, and Mr. Bennet. Elizabeth and Darcy of course learn more about their personal character traits and make changes accordingly. Jane is an example of a character who undergoes emotional changes throughout the story. At the beginning of the book, she is happy, in love, and confident. Then her lover is turned against her and she is heartbroken. Finally, she is reunited and very happy because not only does she get to marry a man she loves, she is helping her family with her fortune. Bingley undergoes emotional changes very similar to Jane's, the only difference is that his emotional changes are caused by other people's persuasion. Mr. Bennet undergoes moral changes, for, due to Lydia's behavior, he realizes just how little he has acted with principles, how little he has taught his family principles, and how much he has let his family get out of control.