Immorality is evil, sinful, or otherwise wrong behavior. Immorality is often called wickedness and is a state avoided by good people.
Since morality refers to things that are right, immorality has to do with things that are wrong — like stealing, lying, and murdering. This is a tricky word, because people have their own idea of what's immoral. We can all agree killing is an example of immorality, but people disagree on whether things such as bad language are truly signs of immorality. Different religions have their own ideas of immorality too, but the word is always associated with wrongness and offensiveness.