Science means many things to many people, but on closer examination it turns out that all the definitions are tightly interconnected. I need to hit the hay in a moment, so I'll briefly run through the stack and maybe comment more tomorrow.
Science is a goal. The goal of science, broadly speaking, is to improve our ability to understand and manipulate the universe. My preferred phrasing is that science attempts to find predictive models of how the world works.
Science is a method. It turns out that a particular pair of approaches (hypothesis testing and peer review), along with a bunch of handy if somewhat ad-hoc guidelines, turn out to be highly effective at helping us to achieve the scientific goal.
Science is a community. The scientific community is a group of people who subject their work to the rigours of the scientific method, with unparalleled success.
Science is a body of knowledge. Or, in my terms, a body of accurate predictive models. This is, of course, an incredibly useful thing to have. This body of knowledge is mostly produced by the scientific community because (more or less by definition) they have the most efficient ways of extending it.
It's important to get these definitions out of the way, because there's a certain amount of equivocation over the term due to these different levels. Each level is not equivalent to the others, but it can be legitimately assumed to be a good approximation thereof. Sometimes this approximation breaks, which is where you get "cargo cult science". More to come.