What are all the different levels of injury severity? What are the characteristics of each level?

Newscasters use terms such as "minor injuries, critically injured, or fatally wounded". How many different "levels" of injury exist? Are there more terms that exist in the medical field as compared to ones that are said on the news. Does each level cover differing amounts/ranges of injuries? I'm sure "minor injuries" is the broadest, while being dead is the least. What is the lowest level...and would a splinter in your finger rank under that level? Is there a cutoff?