What does Madame Loisel's name mean?
This is a very interesting question, and I'll admit it's an idea I'd never thought about before. I did a google search and couldn't find any articles that did more than mention the characters' names. So I thought I'd take a stab at answering your question without backup from the critics.
There are several ancestry web sites for the Oisel family, but I don't think the character in this story has anything to do with them. There is no word "loisel" or "l'oisel" in French, but it is very similar to another term. The French word "oiselle" translates into English as "little bird" or "female bird"; it is from the word "oiseau," which means "bird." So the author may want us to think of Madame Loisel as a little bird who preens with pride and flits from dance partner to dance partner at the ball. Her first name, Mathilde, means "power, strength," and that describes her as well, as she musters all her strength to work to replace Mme Forester's necklace. And that is another interesting name. A forester is not only the caretaker of a forest but is also the one who controls what goes on in the forest. In a sense, Mme Loisel is controlled by Mme Forester in her attempt to replace her friend's lost jewels.
I hope this helps you.