utopian
noun
an idealistic (but usually impractical) social reformer
“a Utopian believes in the ultimate perfectibility of man”
adjective
of or pertaining to or resembling a utopia
“a Utopian novel”
characterized by or aspiring to impracticable perfection
“the dim utopian future”
“utopian idealists”
Oppositesdystopian
Source: WordNet 3.1, Princeton University