In the book, More describes an ideal, fictional island society where everything is perfect, from social justice to economic equality. The term "utopia" is a combination of the Greek words "ou" (not) and "topos" (place), meaning "no place" or "nowhere".
More intentionally used the term to emphasize that his idealized society was purely imaginary and not a real place. However, the word has since come to be used more broadly to refer to any ideal or perfect society, whether real or imagined.