* Animal: If you're thinking about the animal itself, "sheep" could be considered an opposite, as they are often compared and contrasted.
* Meat: The opposite of goat meat (chevon) could be considered beef, pork, or any other common meat.
* Slang: In slang, "goat" can mean "greatest of all time." The opposite of this would be something like "worst of all time."
Let me know if you have a specific context in mind, and I can give you a more accurate answer!