Legal Definition
A third party is an entity, person, or entity that is not the plaintiff or defendant in a legal action or dispute. In contract law, it refers to any other individual or entity whose interests are affected by the legal action, often being sued or sued by the plaintiff/defendant.
Plain-English Translation
Imagine someone who isn't the main person in a lawsuit; they are just another person involved in the legal battle. They might be the person suing or the person being sued, but they aren't the main focus of the case.