A utopia refers to the result or aim of any effort to make the world or humankind perfect. It derives from the book Utopia by Sir Thomas More (1516), about a perfect society where everybody is happy and has everything they need. It has been debated whether the name means "Good Place" or "No Place"-the former is "Eutopia" in Greek, the latter Outopia, and it may have been a pun on his part.
The word "utopian" can be used as a snarl word in many cases. Marxists were accustomed to contrast their "scientific socialism" with the pre-Marxist "utopian" socialist philosophies. It can also be applied, with an equal amount of irony, by conservatives to liberal or leftist reformers.
One drawback a utopian "planner" must deal with is that one person's utopia is often another person's Hell; another is that there are few utopian ideas that are not by now completely worn out.