OC stands for Original Character.

An OC is any character that isn't infringing copyrights. Movie characters are Original Characters. Dora is an Original Character, from her design to her friends to her personality. Fan Characters are not Original Characters. No OCs are 100% original; if another OC has similar looks, it doesn't mean they stole it.

What about the copyright part?
You can't take Dora and call Dora yours (why would you). Nor can you take a design you don't own and call it yours. Technically if you say your wolves are your OCs and you chose the markings and so it's your design, that would be infringing copyrights since the art isn't yours and nowhere did it say you can sell the character, claim the design as your own; no one else can use this design and whatnot. That you'll need to ask Eve. We don't know.

Most adopt shops will tell you if you ask, or already have it in their rules.