Listen to part of the lecture in a biology class. Now, I am kind of confused about it, because the book used that definition to describe mutualism. Could you explain the difference? Good. I was hoping that someone would bring that up, sometimes scientists working in different fields use the term symbiosis to mean slightly different things. And it can get confusing. Um, for example, when symbiosis is used as a synonym for mutualism. But there are quite a few of us out there who think there should be a clearer distinction made between the two. OK, where to begin...um, the original definition of symbiosis is pretty simple, it simply means living together.