This is our last name. Four generations ago a French family emigrated to Poland where the surname apparently thrived because we run into other Polish Dejas occasionally. In Polish the "j" is pronounced like a "y", but most teachers and people in the U.S. who read our name out loud before asking how to pronounce it aspirate the "j" like an "h" for a Spanish word spelled the same way which (we have been told) means the command "go away"!
Even though it has no real "meaning" it is a name.