What does a Pyrrhic victory mean?

I have never heard of this expression before. (Unfortunately there is no medication for ignorance)Bumped into it while reading up on War Elephants.
Background before meaning.
Pyrrhus was a ruler of a minor Grecian kingdom roundabout 300BC. He came to the throne at the age of 12, shortly after the demise of Alexander the Great, and became a brilliant soldier, especially known for his use of elephants in battle.
Anyhow, there was a conflict situation between the Romans and the Greek city of Tarentum in southern Italy. Pyrrhus was asked to help out and he sent 25,000 troops and a bunch of elephants to assist. The Romans were defeated but at great cost. After the battle it is said that he exclaimed, “ Another such victory and we are lost!”
Thus a “Pyrrhic victory”, where the cost of achieving something is so expensive that it is little better than a defeat.
I can relate this to buying special offers. Save this much, save that much, buy before the offer ends etc” in the end you can save yourself into bankruptcy.
Pyrrus died in battle, a tile thrown from a roof killed him during a street battle.
Source was from a book I read while visiting a friend, cannot recall the name. Image from Wikipedia that has lots and lots on Pyrrhus if you are interested.