Prospectus Is a Word for the Forward-Thinking

Like prospect, prospectus looks forward. Thus, a prospectus originally outlined something that didn't yet exist, describing what it would become. This might even be a book; the great dictionary of Noah Webster, like that of Samuel Johnson, was first announced in the form of a prospectus, so that well-to-do people might actually subscribe to it—that is, pay for it in advance so that Webster would have money to live on while writing it. Soon, prospectus was being used to mean a description of a private school or college, intended to attract new students. Today the word very often means a description of a stock offering or mutual fund, whether new or not.