Rectitude refers to behavior that is correct, upright and honorable. You have moral rectitude if you refuse to be involved with a plan that some kids in your class have to cheat on a test.
This is a word that's easy to remember! First of all, rectitude sounds like rector, a member of the clergy, who is supposed to be a person with a highly moral ... 'tude, if you will. It also has the same prefix as rectangle, that most upright of geometric figures. If someone talks about fiscal rectitude, they are concerned with doing the right thing financially.