There is a family of expressions called oxymorons which contain contradicting meanings. What about expressions that add little meaning like "fatally injured"? What are these expressions called?
These are known as tautologies or tautologous expressions.
Some examples from the Guardian Style Guide:
As a side note, tautologies are often found in place names, my favourite is The La Brea Tar Pits, meaning The The Tar Tar Pits.
I've found the word I was looking for. It's pleonasm:
Some better examples:
In the same genre there is also redundancies and tautologies.