One example is autopsy.
The definition is to perform a post-mortem examination to determine the cause of death. I would be rich, however, if I had a nickel for every time I saw this sentence:
An autopsy will be performed to determine the cause of death.
The last six words of that sentence are unnecessary, since they merely repeat what was already said in the first four words.
Just a fun point: A post-mortem examination on an animal other than a human is a necropsy.