Means Gift of God or Given by God. The name Dieudonne strikes me as a name for an intelligent person. Can't really be shortened to anything. I know someone called this who whenever he gets in trouble he says that he's god's gift. Anyway, I like this name.
Louis-Dieudonne was the given name of King Louis XIV of France. Contemporaries regarded him as a divine gift and his birth as a miracle so in a show of gratitude to God for the long-awaited arrival of an heir, he was aptly named Louis-Dieudonné ("God-given") by his parents.
This name is the French form of Deodatus, and thus also a variant form of the French name Déodat. Both Deodatus en Déodat are mentioned in the main database of Behind the Name.